From 44221756ab7515617450400bf23d0e8df486c2b7 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 1 Jul 2021 12:24:46 +0200
Subject: LibJS: Drop "Record" suffix from all the *Environment record classes

"Records" in the spec are basically C++ classes, so let's drop this
mouthful of a suffix.
---
 Userland/Libraries/LibJS/AST.cpp                   |  18 +-
 Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp   |   6 +-
 Userland/Libraries/LibJS/Bytecode/Instruction.h    | 126 ++++++------
 Userland/Libraries/LibJS/Bytecode/Interpreter.cpp  |   6 +-
 Userland/Libraries/LibJS/Bytecode/Op.cpp           |  16 +-
 Userland/Libraries/LibJS/Bytecode/Op.h             |   8 +-
 Userland/Libraries/LibJS/CMakeLists.txt            |  10 +-
 Userland/Libraries/LibJS/Forward.h                 |  10 +-
 Userland/Libraries/LibJS/Heap/Cell.h               |   2 +-
 Userland/Libraries/LibJS/Interpreter.cpp           |  26 +--
 Userland/Libraries/LibJS/Interpreter.h             |   6 +-
 .../Libraries/LibJS/Runtime/AbstractOperations.cpp |  26 +--
 .../Libraries/LibJS/Runtime/AbstractOperations.h   |   8 +-
 Userland/Libraries/LibJS/Runtime/BoundFunction.cpp |   4 +-
 Userland/Libraries/LibJS/Runtime/BoundFunction.h   |   2 +-
 .../LibJS/Runtime/DeclarativeEnvironment.cpp       | 158 +++++++++++++++
 .../LibJS/Runtime/DeclarativeEnvironment.h         |  61 ++++++
 .../LibJS/Runtime/DeclarativeEnvironmentRecord.cpp | 158 ---------------
 .../LibJS/Runtime/DeclarativeEnvironmentRecord.h   |  61 ------
 Userland/Libraries/LibJS/Runtime/Environment.cpp   |  29 +++
 Userland/Libraries/LibJS/Runtime/Environment.h     |  72 +++++++
 .../Libraries/LibJS/Runtime/EnvironmentRecord.cpp  |  29 ---
 .../Libraries/LibJS/Runtime/EnvironmentRecord.h    |  72 -------
 .../LibJS/Runtime/FunctionEnvironment.cpp          |  83 ++++++++
 .../Libraries/LibJS/Runtime/FunctionEnvironment.h  |  66 +++++++
 .../LibJS/Runtime/FunctionEnvironmentRecord.cpp    |  83 --------
 .../LibJS/Runtime/FunctionEnvironmentRecord.h      |  66 -------
 Userland/Libraries/LibJS/Runtime/FunctionObject.h  |   4 +-
 .../Libraries/LibJS/Runtime/GeneratorObject.cpp    |   8 +-
 Userland/Libraries/LibJS/Runtime/GeneratorObject.h |   4 +-
 .../Libraries/LibJS/Runtime/GlobalEnvironment.cpp  | 214 +++++++++++++++++++++
 .../Libraries/LibJS/Runtime/GlobalEnvironment.h    |  61 ++++++
 .../LibJS/Runtime/GlobalEnvironmentRecord.cpp      | 214 ---------------------
 .../LibJS/Runtime/GlobalEnvironmentRecord.h        |  61 ------
 Userland/Libraries/LibJS/Runtime/GlobalObject.cpp  |   6 +-
 Userland/Libraries/LibJS/Runtime/GlobalObject.h    |   6 +-
 .../Libraries/LibJS/Runtime/NativeFunction.cpp     |   2 +-
 Userland/Libraries/LibJS/Runtime/NativeFunction.h  |   2 +-
 .../Libraries/LibJS/Runtime/ObjectEnvironment.cpp  | 116 +++++++++++
 .../Libraries/LibJS/Runtime/ObjectEnvironment.h    |  56 ++++++
 .../LibJS/Runtime/ObjectEnvironmentRecord.cpp      | 116 -----------
 .../LibJS/Runtime/ObjectEnvironmentRecord.h        |  56 ------
 .../LibJS/Runtime/OrdinaryFunctionObject.cpp       |  14 +-
 .../LibJS/Runtime/OrdinaryFunctionObject.h         |  10 +-
 Userland/Libraries/LibJS/Runtime/ProxyObject.cpp   |   4 +-
 Userland/Libraries/LibJS/Runtime/ProxyObject.h     |   2 +-
 Userland/Libraries/LibJS/Runtime/Reference.cpp     |  16 +-
 Userland/Libraries/LibJS/Runtime/Reference.h       |  20 +-
 Userland/Libraries/LibJS/Runtime/VM.cpp            |  70 +++----
 Userland/Libraries/LibJS/Runtime/VM.h              |  24 +--
 50 files changed, 1149 insertions(+), 1149 deletions(-)
 create mode 100644 Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp
 create mode 100644 Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
 delete mode 100644 Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.cpp
 delete mode 100644 Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.h
 create mode 100644 Userland/Libraries/LibJS/Runtime/Environment.cpp
 create mode 100644 Userland/Libraries/LibJS/Runtime/Environment.h
 delete mode 100644 Userland/Libraries/LibJS/Runtime/EnvironmentRecord.cpp
 delete mode 100644 Userland/Libraries/LibJS/Runtime/EnvironmentRecord.h
 create mode 100644 Userland/Libraries/LibJS/Runtime/FunctionEnvironment.cpp
 create mode 100644 Userland/Libraries/LibJS/Runtime/FunctionEnvironment.h
 delete mode 100644 Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.cpp
 delete mode 100644 Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.h
 create mode 100644 Userland/Libraries/LibJS/Runtime/GlobalEnvironment.cpp
 create mode 100644 Userland/Libraries/LibJS/Runtime/GlobalEnvironment.h
 delete mode 100644 Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.cpp
 delete mode 100644 Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.h
 create mode 100644 Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp
 create mode 100644 Userland/Libraries/LibJS/Runtime/ObjectEnvironment.h
 delete mode 100644 Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.cpp
 delete mode 100644 Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.h

(limited to 'Userland')

diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index dd32e7f7c2..66d90aa2bf 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -19,12 +19,12 @@
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/BigInt.h>
 #include <LibJS/Runtime/Error.h>
-#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
+#include <LibJS/Runtime/FunctionEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/IteratorOperations.h>
 #include <LibJS/Runtime/MarkedValueList.h>
 #include <LibJS/Runtime/NativeFunction.h>
-#include <LibJS/Runtime/ObjectEnvironmentRecord.h>
+#include <LibJS/Runtime/ObjectEnvironment.h>
 #include <LibJS/Runtime/OrdinaryFunctionObject.h>
 #include <LibJS/Runtime/PrimitiveString.h>
 #include <LibJS/Runtime/Reference.h>
@@ -133,7 +133,7 @@ CallExpression::ThisAndCallee CallExpression::compute_this_and_callee(Interprete
         Value this_value;
 
         if (is<SuperExpression>(member_expression.object())) {
-            auto super_base = interpreter.current_function_environment_record()->get_super_base();
+            auto super_base = interpreter.current_function_environment()->get_super_base();
             if (super_base.is_nullish()) {
                 vm.throw_exception<TypeError>(global_object, ErrorType::ObjectPrototypeNullOrUndefinedOnSuperPropertyAccess, super_base.to_string_without_side_effects());
                 return {};
@@ -242,7 +242,7 @@ Value CallExpression::execute(Interpreter& interpreter, GlobalObject& global_obj
             return {};
 
         auto& this_er = get_this_environment(interpreter.vm());
-        verify_cast<FunctionEnvironmentRecord>(this_er).bind_this_value(global_object, result);
+        verify_cast<FunctionEnvironment>(this_er).bind_this_value(global_object, result);
     } else {
         result = vm.call(function, this_value, move(arguments));
     }
@@ -305,8 +305,8 @@ Value WithStatement::execute(Interpreter& interpreter, GlobalObject& global_obje
 
     VERIFY(object);
 
-    auto* object_environment_record = new_object_environment(*object, true, interpreter.vm().running_execution_context().lexical_environment);
-    TemporaryChange<EnvironmentRecord*> scope_change(interpreter.vm().running_execution_context().lexical_environment, object_environment_record);
+    auto* object_environment = new_object_environment(*object, true, interpreter.vm().running_execution_context().lexical_environment);
+    TemporaryChange<Environment*> scope_change(interpreter.vm().running_execution_context().lexical_environment, object_environment);
     return interpreter.execute_statement(global_object, m_body).value_or(js_undefined());
 }
 
@@ -854,7 +854,7 @@ Value ClassDeclaration::execute(Interpreter& interpreter, GlobalObject& global_o
     if (interpreter.exception())
         return {};
 
-    interpreter.lexical_environment()->put_into_environment_record(m_class_expression->name(), { class_constructor, DeclarationKind::Let });
+    interpreter.lexical_environment()->put_into_environment(m_class_expression->name(), { class_constructor, DeclarationKind::Let });
 
     return {};
 }
@@ -2049,8 +2049,8 @@ Value TryStatement::execute(Interpreter& interpreter, GlobalObject& global_objec
 
             HashMap<FlyString, Variable> parameters;
             parameters.set(m_handler->parameter(), Variable { exception->value(), DeclarationKind::Var });
-            auto* catch_scope = interpreter.heap().allocate<DeclarativeEnvironmentRecord>(global_object, move(parameters), interpreter.vm().running_execution_context().lexical_environment);
-            TemporaryChange<EnvironmentRecord*> scope_change(interpreter.vm().running_execution_context().lexical_environment, catch_scope);
+            auto* catch_scope = interpreter.heap().allocate<DeclarativeEnvironment>(global_object, move(parameters), interpreter.vm().running_execution_context().lexical_environment);
+            TemporaryChange<Environment*> scope_change(interpreter.vm().running_execution_context().lexical_environment, catch_scope);
             result = interpreter.execute_statement(global_object, m_handler->body());
         }
     }
diff --git a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
index 0c9232c39f..7f02bb0d56 100644
--- a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
@@ -14,7 +14,7 @@
 #include <LibJS/Bytecode/Op.h>
 #include <LibJS/Bytecode/Register.h>
 #include <LibJS/Bytecode/StringTable.h>
-#include <LibJS/Runtime/EnvironmentRecord.h>
+#include <LibJS/Runtime/Environment.h>
 
 namespace JS {
 
@@ -63,7 +63,7 @@ void ScopeNode::generate_bytecode(Bytecode::Generator& generator) const
     }
 
     if (!scope_variables_with_declaration_kind.is_empty()) {
-        generator.emit<Bytecode::Op::PushDeclarativeEnvironmentRecord>(move(scope_variables_with_declaration_kind));
+        generator.emit<Bytecode::Op::PushDeclarativeEnvironment>(move(scope_variables_with_declaration_kind));
     }
 
     for (auto& child : children()) {
@@ -1214,7 +1214,7 @@ void TryStatement::generate_bytecode(Bytecode::Generator& generator) const
         if (!m_finalizer)
             generator.emit<Bytecode::Op::LeaveUnwindContext>();
         if (!m_handler->parameter().is_empty()) {
-            // FIXME: We need a separate DeclarativeEnvironmentRecord here
+            // FIXME: We need a separate DeclarativeEnvironment here
             generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(m_handler->parameter()));
         }
         m_handler->body().generate_bytecode(generator);
diff --git a/Userland/Libraries/LibJS/Bytecode/Instruction.h b/Userland/Libraries/LibJS/Bytecode/Instruction.h
index 8c0e9289dc..2064c4a2b1 100644
--- a/Userland/Libraries/LibJS/Bytecode/Instruction.h
+++ b/Userland/Libraries/LibJS/Bytecode/Instruction.h
@@ -9,69 +9,69 @@
 #include <AK/Forward.h>
 #include <LibJS/Forward.h>
 
-#define ENUMERATE_BYTECODE_OPS(O)       \
-    O(Load)                             \
-    O(LoadImmediate)                    \
-    O(Store)                            \
-    O(Add)                              \
-    O(Sub)                              \
-    O(Mul)                              \
-    O(Div)                              \
-    O(Mod)                              \
-    O(Exp)                              \
-    O(GreaterThan)                      \
-    O(GreaterThanEquals)                \
-    O(LessThan)                         \
-    O(LessThanEquals)                   \
-    O(AbstractInequals)                 \
-    O(AbstractEquals)                   \
-    O(TypedInequals)                    \
-    O(TypedEquals)                      \
-    O(NewBigInt)                        \
-    O(NewArray)                         \
-    O(IteratorToArray)                  \
-    O(NewString)                        \
-    O(NewObject)                        \
-    O(NewRegExp)                        \
-    O(CopyObjectExcludingProperties)    \
-    O(GetVariable)                      \
-    O(SetVariable)                      \
-    O(PutById)                          \
-    O(GetById)                          \
-    O(PutByValue)                       \
-    O(GetByValue)                       \
-    O(Jump)                             \
-    O(JumpConditional)                  \
-    O(JumpNullish)                      \
-    O(JumpUndefined)                    \
-    O(Call)                             \
-    O(NewFunction)                      \
-    O(Return)                           \
-    O(BitwiseAnd)                       \
-    O(BitwiseOr)                        \
-    O(BitwiseXor)                       \
-    O(BitwiseNot)                       \
-    O(Not)                              \
-    O(UnaryPlus)                        \
-    O(UnaryMinus)                       \
-    O(Typeof)                           \
-    O(LeftShift)                        \
-    O(RightShift)                       \
-    O(UnsignedRightShift)               \
-    O(In)                               \
-    O(InstanceOf)                       \
-    O(ConcatString)                     \
-    O(Increment)                        \
-    O(Decrement)                        \
-    O(Throw)                            \
-    O(PushDeclarativeEnvironmentRecord) \
-    O(EnterUnwindContext)               \
-    O(LeaveUnwindContext)               \
-    O(ContinuePendingUnwind)            \
-    O(Yield)                            \
-    O(GetIterator)                      \
-    O(IteratorNext)                     \
-    O(IteratorResultDone)               \
+#define ENUMERATE_BYTECODE_OPS(O)    \
+    O(Load)                          \
+    O(LoadImmediate)                 \
+    O(Store)                         \
+    O(Add)                           \
+    O(Sub)                           \
+    O(Mul)                           \
+    O(Div)                           \
+    O(Mod)                           \
+    O(Exp)                           \
+    O(GreaterThan)                   \
+    O(GreaterThanEquals)             \
+    O(LessThan)                      \
+    O(LessThanEquals)                \
+    O(AbstractInequals)              \
+    O(AbstractEquals)                \
+    O(TypedInequals)                 \
+    O(TypedEquals)                   \
+    O(NewBigInt)                     \
+    O(NewArray)                      \
+    O(IteratorToArray)               \
+    O(NewString)                     \
+    O(NewObject)                     \
+    O(NewRegExp)                     \
+    O(CopyObjectExcludingProperties) \
+    O(GetVariable)                   \
+    O(SetVariable)                   \
+    O(PutById)                       \
+    O(GetById)                       \
+    O(PutByValue)                    \
+    O(GetByValue)                    \
+    O(Jump)                          \
+    O(JumpConditional)               \
+    O(JumpNullish)                   \
+    O(JumpUndefined)                 \
+    O(Call)                          \
+    O(NewFunction)                   \
+    O(Return)                        \
+    O(BitwiseAnd)                    \
+    O(BitwiseOr)                     \
+    O(BitwiseXor)                    \
+    O(BitwiseNot)                    \
+    O(Not)                           \
+    O(UnaryPlus)                     \
+    O(UnaryMinus)                    \
+    O(Typeof)                        \
+    O(LeftShift)                     \
+    O(RightShift)                    \
+    O(UnsignedRightShift)            \
+    O(In)                            \
+    O(InstanceOf)                    \
+    O(ConcatString)                  \
+    O(Increment)                     \
+    O(Decrement)                     \
+    O(Throw)                         \
+    O(PushDeclarativeEnvironment)    \
+    O(EnterUnwindContext)            \
+    O(LeaveUnwindContext)            \
+    O(ContinuePendingUnwind)         \
+    O(Yield)                         \
+    O(GetIterator)                   \
+    O(IteratorNext)                  \
+    O(IteratorResultDone)            \
     O(IteratorResultValue)
 
 namespace JS::Bytecode {
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
index 77072459ba..9e6f04b26f 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -10,7 +10,7 @@
 #include <LibJS/Bytecode/Instruction.h>
 #include <LibJS/Bytecode/Interpreter.h>
 #include <LibJS/Bytecode/Op.h>
-#include <LibJS/Runtime/GlobalEnvironmentRecord.h>
+#include <LibJS/Runtime/GlobalEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 
 namespace JS::Bytecode {
@@ -49,8 +49,8 @@ Value Interpreter::run(Executable const& executable, BasicBlock const* entry_poi
         execution_context.this_value = &global_object();
         static FlyString global_execution_context_name = "(*BC* global execution context)";
         execution_context.function_name = global_execution_context_name;
-        execution_context.lexical_environment = &global_object().environment_record();
-        execution_context.variable_environment = &global_object().environment_record();
+        execution_context.lexical_environment = &global_object().environment();
+        execution_context.variable_environment = &global_object().environment();
         VERIFY(!vm().exception());
         // FIXME: How do we know if we're in strict mode? Maybe the Bytecode::Block should know this?
         // execution_context.is_strict_mode = ???;
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.cpp b/Userland/Libraries/LibJS/Bytecode/Op.cpp
index 521d523c45..c4c6be890f 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Op.cpp
@@ -12,8 +12,8 @@
 #include <LibJS/Bytecode/Op.h>
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/BigInt.h>
-#include <LibJS/Runtime/DeclarativeEnvironmentRecord.h>
-#include <LibJS/Runtime/EnvironmentRecord.h>
+#include <LibJS/Runtime/DeclarativeEnvironment.h>
+#include <LibJS/Runtime/Environment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/IteratorOperations.h>
 #include <LibJS/Runtime/OrdinaryFunctionObject.h>
@@ -381,14 +381,14 @@ void ContinuePendingUnwind::replace_references_impl(BasicBlock const& from, Basi
         m_resume_target = Label { to };
 }
 
-void PushDeclarativeEnvironmentRecord::execute_impl(Bytecode::Interpreter& interpreter) const
+void PushDeclarativeEnvironment::execute_impl(Bytecode::Interpreter& interpreter) const
 {
     HashMap<FlyString, Variable> resolved_variables;
     for (auto& it : m_variables)
         resolved_variables.set(interpreter.current_executable().get_string(it.key), it.value);
-    auto* environment_record = interpreter.vm().heap().allocate<DeclarativeEnvironmentRecord>(interpreter.global_object(), move(resolved_variables), interpreter.vm().lexical_environment());
-    interpreter.vm().running_execution_context().lexical_environment = environment_record;
-    interpreter.vm().running_execution_context().variable_environment = environment_record;
+    auto* environment = interpreter.vm().heap().allocate<DeclarativeEnvironment>(interpreter.global_object(), move(resolved_variables), interpreter.vm().lexical_environment());
+    interpreter.vm().running_execution_context().lexical_environment = environment;
+    interpreter.vm().running_execution_context().variable_environment = environment;
 }
 
 void Yield::execute_impl(Bytecode::Interpreter& interpreter) const
@@ -635,10 +635,10 @@ String ContinuePendingUnwind::to_string_impl(Bytecode::Executable const&) const
     return String::formatted("ContinuePendingUnwind resume:{}", m_resume_target);
 }
 
-String PushDeclarativeEnvironmentRecord::to_string_impl(const Bytecode::Executable& executable) const
+String PushDeclarativeEnvironment::to_string_impl(const Bytecode::Executable& executable) const
 {
     StringBuilder builder;
-    builder.append("PushDeclarativeEnvironmentRecord");
+    builder.append("PushDeclarativeEnvironment");
     if (!m_variables.is_empty()) {
         builder.append(" {");
         Vector<String> names;
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.h b/Userland/Libraries/LibJS/Bytecode/Op.h
index 85cb43d43f..eafbda878f 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.h
+++ b/Userland/Libraries/LibJS/Bytecode/Op.h
@@ -14,7 +14,7 @@
 #include <LibJS/Bytecode/Register.h>
 #include <LibJS/Bytecode/StringTable.h>
 #include <LibJS/Heap/Cell.h>
-#include <LibJS/Runtime/EnvironmentRecord.h>
+#include <LibJS/Runtime/Environment.h>
 #include <LibJS/Runtime/Value.h>
 
 namespace JS::Bytecode::Op {
@@ -635,10 +635,10 @@ private:
     Optional<Label> m_continuation_label;
 };
 
-class PushDeclarativeEnvironmentRecord final : public Instruction {
+class PushDeclarativeEnvironment final : public Instruction {
 public:
-    explicit PushDeclarativeEnvironmentRecord(HashMap<u32, Variable> variables)
-        : Instruction(Type::PushDeclarativeEnvironmentRecord)
+    explicit PushDeclarativeEnvironment(HashMap<u32, Variable> variables)
+        : Instruction(Type::PushDeclarativeEnvironment)
         , m_variables(move(variables))
     {
     }
diff --git a/Userland/Libraries/LibJS/CMakeLists.txt b/Userland/Libraries/LibJS/CMakeLists.txt
index 3a82706afd..fb7af79148 100644
--- a/Userland/Libraries/LibJS/CMakeLists.txt
+++ b/Userland/Libraries/LibJS/CMakeLists.txt
@@ -50,8 +50,8 @@ set(SOURCES
     Runtime/DateConstructor.cpp
     Runtime/Date.cpp
     Runtime/DatePrototype.cpp
-    Runtime/DeclarativeEnvironmentRecord.cpp
-    Runtime/EnvironmentRecord.cpp
+    Runtime/DeclarativeEnvironment.cpp
+    Runtime/Environment.cpp
     Runtime/ErrorConstructor.cpp
     Runtime/Error.cpp
     Runtime/ErrorPrototype.cpp
@@ -61,14 +61,14 @@ set(SOURCES
     Runtime/FinalizationRegistryConstructor.cpp
     Runtime/FinalizationRegistryPrototype.cpp
     Runtime/FunctionConstructor.cpp
-    Runtime/FunctionEnvironmentRecord.cpp
+    Runtime/FunctionEnvironment.cpp
     Runtime/FunctionObject.cpp
     Runtime/FunctionPrototype.cpp
     Runtime/GeneratorFunctionConstructor.cpp
     Runtime/GeneratorFunctionPrototype.cpp
     Runtime/GeneratorObject.cpp
     Runtime/GeneratorObjectPrototype.cpp
-    Runtime/GlobalEnvironmentRecord.cpp
+    Runtime/GlobalEnvironment.cpp
     Runtime/GlobalObject.cpp
     Runtime/IndexedProperties.cpp
     Runtime/IteratorOperations.cpp
@@ -88,7 +88,7 @@ set(SOURCES
     Runtime/NumberPrototype.cpp
     Runtime/Object.cpp
     Runtime/ObjectConstructor.cpp
-    Runtime/ObjectEnvironmentRecord.cpp
+    Runtime/ObjectEnvironment.cpp
     Runtime/ObjectPrototype.cpp
     Runtime/PrimitiveString.cpp
     Runtime/Promise.cpp
diff --git a/Userland/Libraries/LibJS/Forward.h b/Userland/Libraries/LibJS/Forward.h
index 1e56bd0155..3519a7e521 100644
--- a/Userland/Libraries/LibJS/Forward.h
+++ b/Userland/Libraries/LibJS/Forward.h
@@ -120,16 +120,16 @@ class BoundFunction;
 class Cell;
 class CellAllocator;
 class Console;
-class DeclarativeEnvironmentRecord;
+class DeclarativeEnvironment;
 class DeferGC;
-class EnvironmentRecord;
+class Environment;
 class Error;
 class ErrorType;
 class Exception;
 class Expression;
-class FunctionEnvironmentRecord;
+class FunctionEnvironment;
 class FunctionNode;
-class GlobalEnvironmentRecord;
+class GlobalEnvironment;
 class GlobalObject;
 class HandleImpl;
 class Heap;
@@ -138,7 +138,7 @@ class Interpreter;
 class MarkedValueList;
 class NativeFunction;
 class NativeProperty;
-class ObjectEnvironmentRecord;
+class ObjectEnvironment;
 class PrimitiveString;
 class PromiseReaction;
 class PromiseReactionJob;
diff --git a/Userland/Libraries/LibJS/Heap/Cell.h b/Userland/Libraries/LibJS/Heap/Cell.h
index 3e320d8172..764104d84c 100644
--- a/Userland/Libraries/LibJS/Heap/Cell.h
+++ b/Userland/Libraries/LibJS/Heap/Cell.h
@@ -50,7 +50,7 @@ public:
         virtual ~Visitor() = default;
     };
 
-    virtual bool is_environment_record() const { return false; }
+    virtual bool is_environment() const { return false; }
     virtual void visit_edges(Visitor&) { }
 
     Heap& heap() const;
diff --git a/Userland/Libraries/LibJS/Interpreter.cpp b/Userland/Libraries/LibJS/Interpreter.cpp
index 6805cd6879..0b8acd4264 100644
--- a/Userland/Libraries/LibJS/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Interpreter.cpp
@@ -9,8 +9,8 @@
 #include <AK/StringBuilder.h>
 #include <LibJS/AST.h>
 #include <LibJS/Interpreter.h>
-#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
-#include <LibJS/Runtime/GlobalEnvironmentRecord.h>
+#include <LibJS/Runtime/FunctionEnvironment.h>
+#include <LibJS/Runtime/GlobalEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Object.h>
 #include <LibJS/Runtime/OrdinaryFunctionObject.h>
@@ -51,8 +51,8 @@ void Interpreter::run(GlobalObject& global_object, const Program& program)
     execution_context.this_value = &global_object;
     static FlyString global_execution_context_name = "(global execution context)";
     execution_context.function_name = global_execution_context_name;
-    execution_context.lexical_environment = &global_object.environment_record();
-    execution_context.variable_environment = &global_object.environment_record();
+    execution_context.lexical_environment = &global_object.environment();
+    execution_context.variable_environment = &global_object.environment();
     VERIFY(!vm.exception());
     execution_context.is_strict_mode = program.is_strict_mode();
     vm.push_execution_context(execution_context, global_object);
@@ -93,7 +93,7 @@ void Interpreter::enter_scope(const ScopeNode& scope_node, ScopeType scope_type,
     if (scope_type == ScopeType::Function) {
         push_scope({ scope_type, scope_node, false });
         for (auto& declaration : scope_node.functions())
-            lexical_environment()->put_into_environment_record(declaration.name(), { js_undefined(), DeclarationKind::Var });
+            lexical_environment()->put_into_environment(declaration.name(), { js_undefined(), DeclarationKind::Var });
         return;
     }
 
@@ -130,16 +130,16 @@ void Interpreter::enter_scope(const ScopeNode& scope_node, ScopeType scope_type,
         }
     }
 
-    bool pushed_environment_record = false;
+    bool pushed_environment = false;
 
     if (!scope_variables_with_declaration_kind.is_empty()) {
-        auto* environment_record = heap().allocate<DeclarativeEnvironmentRecord>(global_object, move(scope_variables_with_declaration_kind), lexical_environment());
-        vm().running_execution_context().lexical_environment = environment_record;
-        vm().running_execution_context().variable_environment = environment_record;
-        pushed_environment_record = true;
+        auto* environment = heap().allocate<DeclarativeEnvironment>(global_object, move(scope_variables_with_declaration_kind), lexical_environment());
+        vm().running_execution_context().lexical_environment = environment;
+        vm().running_execution_context().variable_environment = environment;
+        pushed_environment = true;
     }
 
-    push_scope({ scope_type, scope_node, pushed_environment_record });
+    push_scope({ scope_type, scope_node, pushed_environment });
 }
 
 void Interpreter::exit_scope(const ScopeNode& scope_node)
@@ -198,9 +198,9 @@ Value Interpreter::execute_statement(GlobalObject& global_object, const Statemen
     return last_value;
 }
 
-FunctionEnvironmentRecord* Interpreter::current_function_environment_record()
+FunctionEnvironment* Interpreter::current_function_environment()
 {
-    return verify_cast<FunctionEnvironmentRecord>(vm().running_execution_context().lexical_environment);
+    return verify_cast<FunctionEnvironment>(vm().running_execution_context().lexical_environment);
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Interpreter.h b/Userland/Libraries/LibJS/Interpreter.h
index a342fc8b10..204cf041d5 100644
--- a/Userland/Libraries/LibJS/Interpreter.h
+++ b/Userland/Libraries/LibJS/Interpreter.h
@@ -15,7 +15,7 @@
 #include <LibJS/Forward.h>
 #include <LibJS/Heap/DeferGC.h>
 #include <LibJS/Heap/Heap.h>
-#include <LibJS/Runtime/DeclarativeEnvironmentRecord.h>
+#include <LibJS/Runtime/DeclarativeEnvironment.h>
 #include <LibJS/Runtime/ErrorTypes.h>
 #include <LibJS/Runtime/Exception.h>
 #include <LibJS/Runtime/MarkedValueList.h>
@@ -56,9 +56,9 @@ public:
     ALWAYS_INLINE Heap& heap() { return vm().heap(); }
     ALWAYS_INLINE Exception* exception() { return vm().exception(); }
 
-    EnvironmentRecord* lexical_environment() { return vm().lexical_environment(); }
+    Environment* lexical_environment() { return vm().lexical_environment(); }
 
-    FunctionEnvironmentRecord* current_function_environment_record();
+    FunctionEnvironment* current_function_environment();
 
     void enter_scope(const ScopeNode&, ScopeType, GlobalObject&);
     void exit_scope(const ScopeNode&);
diff --git a/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp b/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
index 9f045b211f..5e32edcb62 100644
--- a/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
+++ b/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
@@ -15,14 +15,14 @@
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/ArrayPrototype.h>
 #include <LibJS/Runtime/BoundFunction.h>
-#include <LibJS/Runtime/DeclarativeEnvironmentRecord.h>
+#include <LibJS/Runtime/DeclarativeEnvironment.h>
 #include <LibJS/Runtime/ErrorTypes.h>
-#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
+#include <LibJS/Runtime/FunctionEnvironment.h>
 #include <LibJS/Runtime/FunctionObject.h>
-#include <LibJS/Runtime/GlobalEnvironmentRecord.h>
+#include <LibJS/Runtime/GlobalEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Object.h>
-#include <LibJS/Runtime/ObjectEnvironmentRecord.h>
+#include <LibJS/Runtime/ObjectEnvironment.h>
 #include <LibJS/Runtime/PropertyName.h>
 #include <LibJS/Runtime/ProxyObject.h>
 
@@ -148,21 +148,21 @@ Object* get_prototype_from_constructor(GlobalObject& global_object, FunctionObje
 }
 
 // 9.1.2.2 NewDeclarativeEnvironment ( E ), https://tc39.es/ecma262/#sec-newdeclarativeenvironment
-DeclarativeEnvironmentRecord* new_declarative_environment(EnvironmentRecord& environment_record)
+DeclarativeEnvironment* new_declarative_environment(Environment& environment)
 {
-    auto& global_object = environment_record.global_object();
-    return global_object.heap().allocate<DeclarativeEnvironmentRecord>(global_object, &environment_record);
+    auto& global_object = environment.global_object();
+    return global_object.heap().allocate<DeclarativeEnvironment>(global_object, &environment);
 }
 
 // 9.1.2.3 NewObjectEnvironment ( O, W, E ), https://tc39.es/ecma262/#sec-newobjectenvironment
-ObjectEnvironmentRecord* new_object_environment(Object& object, bool is_with_environment, EnvironmentRecord* environment_record)
+ObjectEnvironment* new_object_environment(Object& object, bool is_with_environment, Environment* environment)
 {
     auto& global_object = object.global_object();
-    return global_object.heap().allocate<ObjectEnvironmentRecord>(global_object, object, is_with_environment ? ObjectEnvironmentRecord::IsWithEnvironment::Yes : ObjectEnvironmentRecord::IsWithEnvironment::No, environment_record);
+    return global_object.heap().allocate<ObjectEnvironment>(global_object, object, is_with_environment ? ObjectEnvironment::IsWithEnvironment::Yes : ObjectEnvironment::IsWithEnvironment::No, environment);
 }
 
 // 9.4.3 GetThisEnvironment ( ), https://tc39.es/ecma262/#sec-getthisenvironment
-EnvironmentRecord& get_this_environment(VM& vm)
+Environment& get_this_environment(VM& vm)
 {
     for (auto* env = vm.lexical_environment(); env; env = env->outer_environment()) {
         if (env->has_this_binding())
@@ -175,7 +175,7 @@ EnvironmentRecord& get_this_environment(VM& vm)
 Object* get_super_constructor(VM& vm)
 {
     auto& env = get_this_environment(vm);
-    auto& active_function = verify_cast<FunctionEnvironmentRecord>(env).function_object();
+    auto& active_function = verify_cast<FunctionEnvironment>(env).function_object();
     auto* super_constructor = active_function.prototype();
     return super_constructor;
 }
@@ -202,7 +202,7 @@ Value perform_eval(Value x, GlobalObject& caller_realm, CallerMode strict_caller
     if (direct == EvalMode::Direct)
         return interpreter.execute_statement(caller_realm, program).value_or(js_undefined());
 
-    TemporaryChange scope_change(vm.running_execution_context().lexical_environment, static_cast<EnvironmentRecord*>(&caller_realm.environment_record()));
+    TemporaryChange scope_change(vm.running_execution_context().lexical_environment, static_cast<Environment*>(&caller_realm.environment()));
     return interpreter.execute_statement(caller_realm, program).value_or(js_undefined());
 }
 
@@ -234,7 +234,7 @@ Object* create_unmapped_arguments_object(GlobalObject& global_object, Vector<Val
 }
 
 // 10.4.4.7 CreateMappedArgumentsObject ( func, formals, argumentsList, env ), https://tc39.es/ecma262/#sec-createmappedargumentsobject
-Object* create_mapped_arguments_object(GlobalObject& global_object, FunctionObject& function, Vector<FunctionNode::Parameter> const& formals, Vector<Value> const& arguments, EnvironmentRecord&)
+Object* create_mapped_arguments_object(GlobalObject& global_object, FunctionObject& function, Vector<FunctionNode::Parameter> const& formals, Vector<Value> const& arguments, Environment&)
 {
     // FIXME: This implementation is incomplete and doesn't support the actual identifier mappings yet.
     (void)formals;
diff --git a/Userland/Libraries/LibJS/Runtime/AbstractOperations.h b/Userland/Libraries/LibJS/Runtime/AbstractOperations.h
index ae5edb0602..652fecbd2b 100644
--- a/Userland/Libraries/LibJS/Runtime/AbstractOperations.h
+++ b/Userland/Libraries/LibJS/Runtime/AbstractOperations.h
@@ -14,9 +14,9 @@
 
 namespace JS {
 
-DeclarativeEnvironmentRecord* new_declarative_environment(EnvironmentRecord&);
-ObjectEnvironmentRecord* new_object_environment(Object&, bool is_with_environment, EnvironmentRecord*);
-EnvironmentRecord& get_this_environment(VM&);
+DeclarativeEnvironment* new_declarative_environment(Environment&);
+ObjectEnvironment* new_object_environment(Object&, bool is_with_environment, Environment*);
+Environment& get_this_environment(VM&);
 Object* get_super_constructor(VM&);
 Value require_object_coercible(GlobalObject&, Value);
 size_t length_of_array_like(GlobalObject&, Object const&);
@@ -25,7 +25,7 @@ FunctionObject* species_constructor(GlobalObject&, Object const&, FunctionObject
 GlobalObject* get_function_realm(GlobalObject&, FunctionObject const&);
 Object* get_prototype_from_constructor(GlobalObject&, FunctionObject const& constructor, Object* (GlobalObject::*intrinsic_default_prototype)());
 Object* create_unmapped_arguments_object(GlobalObject&, Vector<Value> const& arguments);
-Object* create_mapped_arguments_object(GlobalObject&, FunctionObject&, Vector<FunctionNode::Parameter> const&, Vector<Value> const& arguments, EnvironmentRecord&);
+Object* create_mapped_arguments_object(GlobalObject&, FunctionObject&, Vector<FunctionNode::Parameter> const&, Vector<Value> const& arguments, Environment&);
 
 enum class CallerMode {
     Strict,
diff --git a/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp b/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp
index ef1d77ceef..f5c35e9200 100644
--- a/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp
+++ b/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp
@@ -44,9 +44,9 @@ Value BoundFunction::construct(FunctionObject& new_target)
     return m_target_function->construct(new_target);
 }
 
-FunctionEnvironmentRecord* BoundFunction::create_environment_record(FunctionObject& function_being_invoked)
+FunctionEnvironment* BoundFunction::create_environment(FunctionObject& function_being_invoked)
 {
-    return m_target_function->create_environment_record(function_being_invoked);
+    return m_target_function->create_environment(function_being_invoked);
 }
 
 void BoundFunction::visit_edges(Visitor& visitor)
diff --git a/Userland/Libraries/LibJS/Runtime/BoundFunction.h b/Userland/Libraries/LibJS/Runtime/BoundFunction.h
index 7af8c915ab..7403b392a3 100644
--- a/Userland/Libraries/LibJS/Runtime/BoundFunction.h
+++ b/Userland/Libraries/LibJS/Runtime/BoundFunction.h
@@ -22,7 +22,7 @@ public:
 
     virtual Value construct(FunctionObject& new_target) override;
 
-    virtual FunctionEnvironmentRecord* create_environment_record(FunctionObject&) override;
+    virtual FunctionEnvironment* create_environment(FunctionObject&) override;
 
     virtual void visit_edges(Visitor&) override;
 
diff --git a/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp b/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp
new file mode 100644
index 0000000000..b200e775be
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Interpreter.h>
+#include <LibJS/Runtime/DeclarativeEnvironment.h>
+#include <LibJS/Runtime/Error.h>
+#include <LibJS/Runtime/FunctionObject.h>
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Value.h>
+
+namespace JS {
+
+DeclarativeEnvironment::DeclarativeEnvironment()
+    : Environment(nullptr)
+{
+}
+
+DeclarativeEnvironment::DeclarativeEnvironment(Environment* parent_scope)
+    : Environment(parent_scope)
+{
+}
+
+DeclarativeEnvironment::DeclarativeEnvironment(HashMap<FlyString, Variable> variables, Environment* parent_scope)
+    : Environment(parent_scope)
+    , m_variables(move(variables))
+{
+}
+
+DeclarativeEnvironment::~DeclarativeEnvironment()
+{
+}
+
+void DeclarativeEnvironment::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    for (auto& it : m_variables)
+        visitor.visit(it.value.value);
+    for (auto& it : m_bindings)
+        visitor.visit(it.value.value);
+}
+
+Optional<Variable> DeclarativeEnvironment::get_from_environment(FlyString const& name) const
+{
+    return m_variables.get(name);
+}
+
+void DeclarativeEnvironment::put_into_environment(FlyString const& name, Variable variable)
+{
+    m_variables.set(name, variable);
+}
+
+bool DeclarativeEnvironment::delete_from_environment(FlyString const& name)
+{
+    return m_variables.remove(name);
+}
+
+// 9.1.1.1.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-hasbinding-n
+bool DeclarativeEnvironment::has_binding(FlyString const& name) const
+{
+    return m_bindings.contains(name);
+}
+
+// 9.1.1.1.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-declarative-environment-records-createmutablebinding-n-d
+void DeclarativeEnvironment::create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted)
+{
+    auto result = m_bindings.set(name,
+        Binding {
+            .value = {},
+            .strict = false,
+            .mutable_ = true,
+            .can_be_deleted = can_be_deleted,
+            .initialized = false,
+        });
+    VERIFY(result == AK::HashSetResult::InsertedNewEntry);
+}
+
+// 9.1.1.1.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-createimmutablebinding-n-s
+void DeclarativeEnvironment::create_immutable_binding(GlobalObject&, FlyString const& name, bool strict)
+{
+    auto result = m_bindings.set(name,
+        Binding {
+            .value = {},
+            .strict = strict,
+            .mutable_ = false,
+            .can_be_deleted = false,
+            .initialized = false,
+        });
+    VERIFY(result == AK::HashSetResult::InsertedNewEntry);
+}
+
+// 9.1.1.1.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-declarative-environment-records-initializebinding-n-v
+void DeclarativeEnvironment::initialize_binding(GlobalObject&, FlyString const& name, Value value)
+{
+    auto it = m_bindings.find(name);
+    VERIFY(it != m_bindings.end());
+    VERIFY(it->value.initialized == false);
+    it->value.value = value;
+    it->value.initialized = true;
+}
+
+// 9.1.1.1.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-setmutablebinding-n-v-s
+void DeclarativeEnvironment::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
+{
+    auto it = m_bindings.find(name);
+    if (it == m_bindings.end()) {
+        if (strict) {
+            global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
+            return;
+        }
+        create_mutable_binding(global_object, name, true);
+        initialize_binding(global_object, name, value);
+        return;
+    }
+
+    if (it->value.strict)
+        strict = true;
+
+    if (!it->value.initialized) {
+        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
+        return;
+    }
+
+    if (it->value.mutable_) {
+        it->value.value = value;
+    } else {
+        if (strict) {
+            global_object.vm().throw_exception<TypeError>(global_object, ErrorType::InvalidAssignToConst);
+        }
+    }
+}
+
+// 9.1.1.1.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-getbindingvalue-n-s
+Value DeclarativeEnvironment::get_binding_value(GlobalObject& global_object, FlyString const& name, bool)
+{
+    auto it = m_bindings.find(name);
+    VERIFY(it != m_bindings.end());
+    if (!it->value.initialized) {
+        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
+        return {};
+    }
+    return it->value.value;
+}
+
+// 9.1.1.1.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-deletebinding-n
+bool DeclarativeEnvironment::delete_binding(GlobalObject&, FlyString const& name)
+{
+    auto it = m_bindings.find(name);
+    VERIFY(it != m_bindings.end());
+    if (!it->value.can_be_deleted)
+        return false;
+    m_bindings.remove(it);
+    return true;
+}
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h b/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
new file mode 100644
index 0000000000..1e1c3149e4
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/FlyString.h>
+#include <AK/HashMap.h>
+#include <LibJS/Runtime/Environment.h>
+#include <LibJS/Runtime/Value.h>
+
+namespace JS {
+
+struct Binding {
+    Value value;
+    bool strict;
+    bool mutable_ { false };
+    bool can_be_deleted { false };
+    bool initialized { false };
+};
+
+class DeclarativeEnvironment : public Environment {
+    JS_ENVIRONMENT(DeclarativeEnvironment, Environment);
+
+public:
+    DeclarativeEnvironment();
+    explicit DeclarativeEnvironment(Environment* parent_scope);
+    DeclarativeEnvironment(HashMap<FlyString, Variable> variables, Environment* parent_scope);
+    virtual ~DeclarativeEnvironment() override;
+
+    // ^Environment
+    virtual Optional<Variable> get_from_environment(FlyString const&) const override;
+    virtual void put_into_environment(FlyString const&, Variable) override;
+    virtual bool delete_from_environment(FlyString const&) override;
+
+    HashMap<FlyString, Variable> const& variables() const { return m_variables; }
+
+    virtual bool has_binding(FlyString const& name) const override;
+    virtual void create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
+    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
+    virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
+    virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual bool delete_binding(GlobalObject&, FlyString const& name) override;
+
+protected:
+    virtual void visit_edges(Visitor&) override;
+
+private:
+    virtual bool is_declarative_environment() const override { return true; }
+
+    HashMap<FlyString, Variable> m_variables;
+    HashMap<FlyString, Binding> m_bindings;
+};
+
+template<>
+inline bool Environment::fast_is<DeclarativeEnvironment>() const { return is_declarative_environment(); }
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.cpp b/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.cpp
deleted file mode 100644
index 6e075e5be1..0000000000
--- a/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.cpp
+++ /dev/null
@@ -1,158 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include <LibJS/Interpreter.h>
-#include <LibJS/Runtime/DeclarativeEnvironmentRecord.h>
-#include <LibJS/Runtime/Error.h>
-#include <LibJS/Runtime/FunctionObject.h>
-#include <LibJS/Runtime/GlobalObject.h>
-#include <LibJS/Runtime/Value.h>
-
-namespace JS {
-
-DeclarativeEnvironmentRecord::DeclarativeEnvironmentRecord()
-    : EnvironmentRecord(nullptr)
-{
-}
-
-DeclarativeEnvironmentRecord::DeclarativeEnvironmentRecord(EnvironmentRecord* parent_scope)
-    : EnvironmentRecord(parent_scope)
-{
-}
-
-DeclarativeEnvironmentRecord::DeclarativeEnvironmentRecord(HashMap<FlyString, Variable> variables, EnvironmentRecord* parent_scope)
-    : EnvironmentRecord(parent_scope)
-    , m_variables(move(variables))
-{
-}
-
-DeclarativeEnvironmentRecord::~DeclarativeEnvironmentRecord()
-{
-}
-
-void DeclarativeEnvironmentRecord::visit_edges(Visitor& visitor)
-{
-    Base::visit_edges(visitor);
-    for (auto& it : m_variables)
-        visitor.visit(it.value.value);
-    for (auto& it : m_bindings)
-        visitor.visit(it.value.value);
-}
-
-Optional<Variable> DeclarativeEnvironmentRecord::get_from_environment_record(FlyString const& name) const
-{
-    return m_variables.get(name);
-}
-
-void DeclarativeEnvironmentRecord::put_into_environment_record(FlyString const& name, Variable variable)
-{
-    m_variables.set(name, variable);
-}
-
-bool DeclarativeEnvironmentRecord::delete_from_environment_record(FlyString const& name)
-{
-    return m_variables.remove(name);
-}
-
-// 9.1.1.1.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-hasbinding-n
-bool DeclarativeEnvironmentRecord::has_binding(FlyString const& name) const
-{
-    return m_bindings.contains(name);
-}
-
-// 9.1.1.1.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-declarative-environment-records-createmutablebinding-n-d
-void DeclarativeEnvironmentRecord::create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted)
-{
-    auto result = m_bindings.set(name,
-        Binding {
-            .value = {},
-            .strict = false,
-            .mutable_ = true,
-            .can_be_deleted = can_be_deleted,
-            .initialized = false,
-        });
-    VERIFY(result == AK::HashSetResult::InsertedNewEntry);
-}
-
-// 9.1.1.1.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-createimmutablebinding-n-s
-void DeclarativeEnvironmentRecord::create_immutable_binding(GlobalObject&, FlyString const& name, bool strict)
-{
-    auto result = m_bindings.set(name,
-        Binding {
-            .value = {},
-            .strict = strict,
-            .mutable_ = false,
-            .can_be_deleted = false,
-            .initialized = false,
-        });
-    VERIFY(result == AK::HashSetResult::InsertedNewEntry);
-}
-
-// 9.1.1.1.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-declarative-environment-records-initializebinding-n-v
-void DeclarativeEnvironmentRecord::initialize_binding(GlobalObject&, FlyString const& name, Value value)
-{
-    auto it = m_bindings.find(name);
-    VERIFY(it != m_bindings.end());
-    VERIFY(it->value.initialized == false);
-    it->value.value = value;
-    it->value.initialized = true;
-}
-
-// 9.1.1.1.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-setmutablebinding-n-v-s
-void DeclarativeEnvironmentRecord::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
-{
-    auto it = m_bindings.find(name);
-    if (it == m_bindings.end()) {
-        if (strict) {
-            global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
-            return;
-        }
-        create_mutable_binding(global_object, name, true);
-        initialize_binding(global_object, name, value);
-        return;
-    }
-
-    if (it->value.strict)
-        strict = true;
-
-    if (!it->value.initialized) {
-        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
-        return;
-    }
-
-    if (it->value.mutable_) {
-        it->value.value = value;
-    } else {
-        if (strict) {
-            global_object.vm().throw_exception<TypeError>(global_object, ErrorType::InvalidAssignToConst);
-        }
-    }
-}
-
-// 9.1.1.1.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-getbindingvalue-n-s
-Value DeclarativeEnvironmentRecord::get_binding_value(GlobalObject& global_object, FlyString const& name, bool)
-{
-    auto it = m_bindings.find(name);
-    VERIFY(it != m_bindings.end());
-    if (!it->value.initialized) {
-        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
-        return {};
-    }
-    return it->value.value;
-}
-
-// 9.1.1.1.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-deletebinding-n
-bool DeclarativeEnvironmentRecord::delete_binding(GlobalObject&, FlyString const& name)
-{
-    auto it = m_bindings.find(name);
-    VERIFY(it != m_bindings.end());
-    if (!it->value.can_be_deleted)
-        return false;
-    m_bindings.remove(it);
-    return true;
-}
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.h b/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.h
deleted file mode 100644
index c463959399..0000000000
--- a/Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <AK/FlyString.h>
-#include <AK/HashMap.h>
-#include <LibJS/Runtime/EnvironmentRecord.h>
-#include <LibJS/Runtime/Value.h>
-
-namespace JS {
-
-struct Binding {
-    Value value;
-    bool strict;
-    bool mutable_ { false };
-    bool can_be_deleted { false };
-    bool initialized { false };
-};
-
-class DeclarativeEnvironmentRecord : public EnvironmentRecord {
-    JS_ENVIRONMENT_RECORD(DeclarativeEnvironmentRecord, EnvironmentRecord);
-
-public:
-    DeclarativeEnvironmentRecord();
-    explicit DeclarativeEnvironmentRecord(EnvironmentRecord* parent_scope);
-    DeclarativeEnvironmentRecord(HashMap<FlyString, Variable> variables, EnvironmentRecord* parent_scope);
-    virtual ~DeclarativeEnvironmentRecord() override;
-
-    // ^EnvironmentRecord
-    virtual Optional<Variable> get_from_environment_record(FlyString const&) const override;
-    virtual void put_into_environment_record(FlyString const&, Variable) override;
-    virtual bool delete_from_environment_record(FlyString const&) override;
-
-    HashMap<FlyString, Variable> const& variables() const { return m_variables; }
-
-    virtual bool has_binding(FlyString const& name) const override;
-    virtual void create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
-    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
-    virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
-    virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
-    virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;
-    virtual bool delete_binding(GlobalObject&, FlyString const& name) override;
-
-protected:
-    virtual void visit_edges(Visitor&) override;
-
-private:
-    virtual bool is_declarative_environment_record() const override { return true; }
-
-    HashMap<FlyString, Variable> m_variables;
-    HashMap<FlyString, Binding> m_bindings;
-};
-
-template<>
-inline bool EnvironmentRecord::fast_is<DeclarativeEnvironmentRecord>() const { return is_declarative_environment_record(); }
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/Environment.cpp b/Userland/Libraries/LibJS/Runtime/Environment.cpp
new file mode 100644
index 0000000000..37722c06a3
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/Environment.cpp
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/Environment.h>
+#include <LibJS/Runtime/VM.h>
+
+namespace JS {
+
+Environment::Environment(Environment* outer_environment)
+    : m_outer_environment(outer_environment)
+{
+}
+
+void Environment::initialize(GlobalObject& global_object)
+{
+    m_global_object = &global_object;
+    Cell::initialize(global_object);
+}
+
+void Environment::visit_edges(Visitor& visitor)
+{
+    Cell::visit_edges(visitor);
+    visitor.visit(m_outer_environment);
+}
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/Environment.h b/Userland/Libraries/LibJS/Runtime/Environment.h
new file mode 100644
index 0000000000..0ed71f8965
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/Environment.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/Object.h>
+
+namespace JS {
+
+struct Variable {
+    Value value;
+    DeclarationKind declaration_kind;
+};
+
+#define JS_ENVIRONMENT(class_, base_class) \
+public:                                    \
+    using Base = base_class;               \
+    virtual char const* class_name() const override { return #class_; }
+
+class Environment : public Cell {
+public:
+    GlobalObject& global_object() { return *m_global_object; }
+    GlobalObject const& global_object() const { return *m_global_object; }
+
+    virtual void initialize(GlobalObject&) override;
+
+    virtual Optional<Variable> get_from_environment(FlyString const&) const = 0;
+    virtual void put_into_environment(FlyString const&, Variable) = 0;
+    virtual bool delete_from_environment(FlyString const&) = 0;
+
+    virtual bool has_this_binding() const { return false; }
+    virtual Value get_this_binding(GlobalObject&) const { return {}; }
+
+    virtual Object* with_base_object() const { return nullptr; }
+
+    virtual bool has_binding([[maybe_unused]] FlyString const& name) const { return false; }
+    virtual void create_mutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool can_be_deleted) { }
+    virtual void create_immutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { }
+    virtual void initialize_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, Value) { }
+    virtual void set_mutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, Value, [[maybe_unused]] bool strict) { }
+    virtual Value get_binding_value(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { return {}; }
+    virtual bool delete_binding(GlobalObject&, [[maybe_unused]] FlyString const& name) { return false; }
+
+    // [[OuterEnv]]
+    Environment* outer_environment() { return m_outer_environment; }
+    Environment const* outer_environment() const { return m_outer_environment; }
+
+    virtual bool is_global_environment() const { return false; }
+    virtual bool is_declarative_environment() const { return false; }
+    virtual bool is_function_environment() const { return false; }
+
+    template<typename T>
+    bool fast_is() const = delete;
+
+    virtual char const* class_name() const override { return "Environment"; }
+
+protected:
+    explicit Environment(Environment* parent);
+
+    virtual void visit_edges(Visitor&) override;
+
+private:
+    virtual bool is_environment() const final { return true; }
+
+    GlobalObject* m_global_object { nullptr };
+    Environment* m_outer_environment { nullptr };
+};
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/EnvironmentRecord.cpp b/Userland/Libraries/LibJS/Runtime/EnvironmentRecord.cpp
deleted file mode 100644
index fc9e5687f4..0000000000
--- a/Userland/Libraries/LibJS/Runtime/EnvironmentRecord.cpp
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include <LibJS/Runtime/EnvironmentRecord.h>
-#include <LibJS/Runtime/VM.h>
-
-namespace JS {
-
-EnvironmentRecord::EnvironmentRecord(EnvironmentRecord* outer_environment)
-    : m_outer_environment(outer_environment)
-{
-}
-
-void EnvironmentRecord::initialize(GlobalObject& global_object)
-{
-    m_global_object = &global_object;
-    Cell::initialize(global_object);
-}
-
-void EnvironmentRecord::visit_edges(Visitor& visitor)
-{
-    Cell::visit_edges(visitor);
-    visitor.visit(m_outer_environment);
-}
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/EnvironmentRecord.h b/Userland/Libraries/LibJS/Runtime/EnvironmentRecord.h
deleted file mode 100644
index 443165818a..0000000000
--- a/Userland/Libraries/LibJS/Runtime/EnvironmentRecord.h
+++ /dev/null
@@ -1,72 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <LibJS/Runtime/Object.h>
-
-namespace JS {
-
-struct Variable {
-    Value value;
-    DeclarationKind declaration_kind;
-};
-
-#define JS_ENVIRONMENT_RECORD(class_, base_class) \
-public:                                           \
-    using Base = base_class;                      \
-    virtual char const* class_name() const override { return #class_; }
-
-class EnvironmentRecord : public Cell {
-public:
-    GlobalObject& global_object() { return *m_global_object; }
-    GlobalObject const& global_object() const { return *m_global_object; }
-
-    virtual void initialize(GlobalObject&) override;
-
-    virtual Optional<Variable> get_from_environment_record(FlyString const&) const = 0;
-    virtual void put_into_environment_record(FlyString const&, Variable) = 0;
-    virtual bool delete_from_environment_record(FlyString const&) = 0;
-
-    virtual bool has_this_binding() const { return false; }
-    virtual Value get_this_binding(GlobalObject&) const { return {}; }
-
-    virtual Object* with_base_object() const { return nullptr; }
-
-    virtual bool has_binding([[maybe_unused]] FlyString const& name) const { return false; }
-    virtual void create_mutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool can_be_deleted) { }
-    virtual void create_immutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { }
-    virtual void initialize_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, Value) { }
-    virtual void set_mutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, Value, [[maybe_unused]] bool strict) { }
-    virtual Value get_binding_value(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { return {}; }
-    virtual bool delete_binding(GlobalObject&, [[maybe_unused]] FlyString const& name) { return false; }
-
-    // [[OuterEnv]]
-    EnvironmentRecord* outer_environment() { return m_outer_environment; }
-    EnvironmentRecord const* outer_environment() const { return m_outer_environment; }
-
-    virtual bool is_global_environment_record() const { return false; }
-    virtual bool is_declarative_environment_record() const { return false; }
-    virtual bool is_function_environment_record() const { return false; }
-
-    template<typename T>
-    bool fast_is() const = delete;
-
-    virtual char const* class_name() const override { return "EnvironmentRecord"; }
-
-protected:
-    explicit EnvironmentRecord(EnvironmentRecord* parent);
-
-    virtual void visit_edges(Visitor&) override;
-
-private:
-    virtual bool is_environment_record() const final { return true; }
-
-    GlobalObject* m_global_object { nullptr };
-    EnvironmentRecord* m_outer_environment { nullptr };
-};
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionEnvironment.cpp b/Userland/Libraries/LibJS/Runtime/FunctionEnvironment.cpp
new file mode 100644
index 0000000000..722a5e55c7
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/FunctionEnvironment.cpp
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Interpreter.h>
+#include <LibJS/Runtime/FunctionEnvironment.h>
+#include <LibJS/Runtime/FunctionObject.h>
+#include <LibJS/Runtime/GlobalObject.h>
+
+namespace JS {
+
+FunctionEnvironment::FunctionEnvironment(Environment* parent_scope, HashMap<FlyString, Variable> variables)
+    : DeclarativeEnvironment(variables, parent_scope)
+{
+}
+
+FunctionEnvironment::~FunctionEnvironment()
+{
+}
+
+void FunctionEnvironment::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_this_value);
+    visitor.visit(m_new_target);
+    visitor.visit(m_function_object);
+}
+
+// 9.1.1.3.5 GetSuperBase ( ), https://tc39.es/ecma262/#sec-getsuperbase
+Value FunctionEnvironment::get_super_base() const
+{
+    VERIFY(m_function_object);
+    auto home_object = m_function_object->home_object();
+    if (home_object.is_undefined())
+        return js_undefined();
+    return home_object.as_object().prototype();
+}
+
+// 9.1.1.3.2 HasThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hasthisbinding
+bool FunctionEnvironment::has_this_binding() const
+{
+    if (this_binding_status() == ThisBindingStatus::Lexical)
+        return false;
+    return true;
+}
+
+// 9.1.1.3.3 HasSuperBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hassuperbinding
+bool FunctionEnvironment::has_super_binding() const
+{
+    if (this_binding_status() == ThisBindingStatus::Lexical)
+        return false;
+    if (function_object().home_object().is_undefined())
+        return false;
+    return true;
+}
+
+// 9.1.1.3.4 GetThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-getthisbinding
+Value FunctionEnvironment::get_this_binding(GlobalObject& global_object) const
+{
+    VERIFY(has_this_binding());
+    if (this_binding_status() == ThisBindingStatus::Uninitialized) {
+        vm().throw_exception<ReferenceError>(global_object, ErrorType::ThisHasNotBeenInitialized);
+        return {};
+    }
+    return m_this_value;
+}
+
+// 9.1.1.3.1 BindThisValue ( V ), https://tc39.es/ecma262/#sec-bindthisvalue
+Value FunctionEnvironment::bind_this_value(GlobalObject& global_object, Value this_value)
+{
+    VERIFY(this_binding_status() != ThisBindingStatus::Lexical);
+    if (this_binding_status() == ThisBindingStatus::Initialized) {
+        vm().throw_exception<ReferenceError>(global_object, ErrorType::ThisIsAlreadyInitialized);
+        return {};
+    }
+    m_this_value = this_value;
+    m_this_binding_status = ThisBindingStatus::Initialized;
+    return this_value;
+}
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionEnvironment.h b/Userland/Libraries/LibJS/Runtime/FunctionEnvironment.h
new file mode 100644
index 0000000000..83f63b0173
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/FunctionEnvironment.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/DeclarativeEnvironment.h>
+
+namespace JS {
+
+class FunctionEnvironment final : public DeclarativeEnvironment {
+    JS_ENVIRONMENT(FunctionEnvironment, DeclarativeEnvironment);
+
+public:
+    enum class ThisBindingStatus : u8 {
+        Lexical,
+        Initialized,
+        Uninitialized,
+    };
+
+    FunctionEnvironment(Environment* parent_scope, HashMap<FlyString, Variable> variables);
+    virtual ~FunctionEnvironment() override;
+
+    // [[ThisValue]]
+    Value this_value() const { return m_this_value; }
+    void set_this_value(Value value) { m_this_value = value; }
+
+    // Not a standard operation.
+    void replace_this_binding(Value this_value) { m_this_value = this_value; }
+
+    // [[ThisBindingStatus]]
+    ThisBindingStatus this_binding_status() const { return m_this_binding_status; }
+    void set_this_binding_status(ThisBindingStatus status) { m_this_binding_status = status; }
+
+    // [[FunctionObject]]
+    FunctionObject& function_object() { return *m_function_object; }
+    FunctionObject const& function_object() const { return *m_function_object; }
+    void set_function_object(FunctionObject& function) { m_function_object = &function; }
+
+    // [[NewTarget]]
+    Value new_target() const { return m_new_target; }
+    void set_new_target(Value new_target) { m_new_target = new_target; }
+
+    // Abstract operations
+    Value get_super_base() const;
+    bool has_super_binding() const;
+    virtual bool has_this_binding() const override;
+    virtual Value get_this_binding(GlobalObject&) const override;
+    Value bind_this_value(GlobalObject&, Value);
+
+private:
+    virtual bool is_function_environment() const override { return true; }
+    virtual void visit_edges(Visitor&) override;
+
+    Value m_this_value;
+    ThisBindingStatus m_this_binding_status { ThisBindingStatus::Uninitialized };
+    FunctionObject* m_function_object { nullptr };
+    Value m_new_target;
+};
+
+template<>
+inline bool Environment::fast_is<FunctionEnvironment>() const { return is_function_environment(); }
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.cpp b/Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.cpp
deleted file mode 100644
index 3819fbb7cb..0000000000
--- a/Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.cpp
+++ /dev/null
@@ -1,83 +0,0 @@
-/*
- * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include <LibJS/Interpreter.h>
-#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
-#include <LibJS/Runtime/FunctionObject.h>
-#include <LibJS/Runtime/GlobalObject.h>
-
-namespace JS {
-
-FunctionEnvironmentRecord::FunctionEnvironmentRecord(EnvironmentRecord* parent_scope, HashMap<FlyString, Variable> variables)
-    : DeclarativeEnvironmentRecord(variables, parent_scope)
-{
-}
-
-FunctionEnvironmentRecord::~FunctionEnvironmentRecord()
-{
-}
-
-void FunctionEnvironmentRecord::visit_edges(Visitor& visitor)
-{
-    Base::visit_edges(visitor);
-    visitor.visit(m_this_value);
-    visitor.visit(m_new_target);
-    visitor.visit(m_function_object);
-}
-
-// 9.1.1.3.5 GetSuperBase ( ), https://tc39.es/ecma262/#sec-getsuperbase
-Value FunctionEnvironmentRecord::get_super_base() const
-{
-    VERIFY(m_function_object);
-    auto home_object = m_function_object->home_object();
-    if (home_object.is_undefined())
-        return js_undefined();
-    return home_object.as_object().prototype();
-}
-
-// 9.1.1.3.2 HasThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hasthisbinding
-bool FunctionEnvironmentRecord::has_this_binding() const
-{
-    if (this_binding_status() == ThisBindingStatus::Lexical)
-        return false;
-    return true;
-}
-
-// 9.1.1.3.3 HasSuperBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hassuperbinding
-bool FunctionEnvironmentRecord::has_super_binding() const
-{
-    if (this_binding_status() == ThisBindingStatus::Lexical)
-        return false;
-    if (function_object().home_object().is_undefined())
-        return false;
-    return true;
-}
-
-// 9.1.1.3.4 GetThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-getthisbinding
-Value FunctionEnvironmentRecord::get_this_binding(GlobalObject& global_object) const
-{
-    VERIFY(has_this_binding());
-    if (this_binding_status() == ThisBindingStatus::Uninitialized) {
-        vm().throw_exception<ReferenceError>(global_object, ErrorType::ThisHasNotBeenInitialized);
-        return {};
-    }
-    return m_this_value;
-}
-
-// 9.1.1.3.1 BindThisValue ( V ), https://tc39.es/ecma262/#sec-bindthisvalue
-Value FunctionEnvironmentRecord::bind_this_value(GlobalObject& global_object, Value this_value)
-{
-    VERIFY(this_binding_status() != ThisBindingStatus::Lexical);
-    if (this_binding_status() == ThisBindingStatus::Initialized) {
-        vm().throw_exception<ReferenceError>(global_object, ErrorType::ThisIsAlreadyInitialized);
-        return {};
-    }
-    m_this_value = this_value;
-    m_this_binding_status = ThisBindingStatus::Initialized;
-    return this_value;
-}
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.h b/Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.h
deleted file mode 100644
index aca3a8a223..0000000000
--- a/Userland/Libraries/LibJS/Runtime/FunctionEnvironmentRecord.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <LibJS/Runtime/DeclarativeEnvironmentRecord.h>
-
-namespace JS {
-
-class FunctionEnvironmentRecord final : public DeclarativeEnvironmentRecord {
-    JS_ENVIRONMENT_RECORD(FunctionEnvironmentRecord, DeclarativeEnvironmentRecord);
-
-public:
-    enum class ThisBindingStatus : u8 {
-        Lexical,
-        Initialized,
-        Uninitialized,
-    };
-
-    FunctionEnvironmentRecord(EnvironmentRecord* parent_scope, HashMap<FlyString, Variable> variables);
-    virtual ~FunctionEnvironmentRecord() override;
-
-    // [[ThisValue]]
-    Value this_value() const { return m_this_value; }
-    void set_this_value(Value value) { m_this_value = value; }
-
-    // Not a standard operation.
-    void replace_this_binding(Value this_value) { m_this_value = this_value; }
-
-    // [[ThisBindingStatus]]
-    ThisBindingStatus this_binding_status() const { return m_this_binding_status; }
-    void set_this_binding_status(ThisBindingStatus status) { m_this_binding_status = status; }
-
-    // [[FunctionObject]]
-    FunctionObject& function_object() { return *m_function_object; }
-    FunctionObject const& function_object() const { return *m_function_object; }
-    void set_function_object(FunctionObject& function) { m_function_object = &function; }
-
-    // [[NewTarget]]
-    Value new_target() const { return m_new_target; }
-    void set_new_target(Value new_target) { m_new_target = new_target; }
-
-    // Abstract operations
-    Value get_super_base() const;
-    bool has_super_binding() const;
-    virtual bool has_this_binding() const override;
-    virtual Value get_this_binding(GlobalObject&) const override;
-    Value bind_this_value(GlobalObject&, Value);
-
-private:
-    virtual bool is_function_environment_record() const override { return true; }
-    virtual void visit_edges(Visitor&) override;
-
-    Value m_this_value;
-    ThisBindingStatus m_this_binding_status { ThisBindingStatus::Uninitialized };
-    FunctionObject* m_function_object { nullptr };
-    Value m_new_target;
-};
-
-template<>
-inline bool EnvironmentRecord::fast_is<FunctionEnvironmentRecord>() const { return is_function_environment_record(); }
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionObject.h b/Userland/Libraries/LibJS/Runtime/FunctionObject.h
index 91f5b35cd7..c98d4fc141 100644
--- a/Userland/Libraries/LibJS/Runtime/FunctionObject.h
+++ b/Userland/Libraries/LibJS/Runtime/FunctionObject.h
@@ -26,7 +26,7 @@ public:
     virtual Value call() = 0;
     virtual Value construct(FunctionObject& new_target) = 0;
     virtual const FlyString& name() const = 0;
-    virtual FunctionEnvironmentRecord* create_environment_record(FunctionObject&) = 0;
+    virtual FunctionEnvironment* create_environment(FunctionObject&) = 0;
 
     BoundFunction* bind(Value bound_this_value, Vector<Value> arguments);
 
@@ -45,7 +45,7 @@ public:
     // [[Environment]]
     // The Environment Record that the function was closed over.
     // Used as the outer environment when evaluating the code of the function.
-    virtual EnvironmentRecord* environment() { return nullptr; }
+    virtual Environment* environment() { return nullptr; }
 
     // [[Realm]]
     virtual GlobalObject* realm() const { return nullptr; }
diff --git a/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp b/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp
index b05f24d6b0..351e094fa3 100644
--- a/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp
@@ -13,7 +13,7 @@
 
 namespace JS {
 
-GeneratorObject* GeneratorObject::create(GlobalObject& global_object, Value initial_value, OrdinaryFunctionObject* generating_function, EnvironmentRecord* generating_scope, Bytecode::RegisterWindow frame)
+GeneratorObject* GeneratorObject::create(GlobalObject& global_object, Value initial_value, OrdinaryFunctionObject* generating_function, Environment* generating_scope, Bytecode::RegisterWindow frame)
 {
     // This is "g1.prototype" in figure-2 (https://tc39.es/ecma262/img/figure-2.png)
     auto generating_function_proto_property = generating_function->get(global_object.vm().names.prototype).to_object(global_object);
@@ -22,7 +22,7 @@ GeneratorObject* GeneratorObject::create(GlobalObject& global_object, Value init
 
     auto object = global_object.heap().allocate<GeneratorObject>(global_object, global_object, *generating_function_proto_property);
     object->m_generating_function = generating_function;
-    object->m_environment_record = generating_scope;
+    object->m_environment = generating_scope;
     object->m_frame = move(frame);
     object->m_previous_value = initial_value;
     return object;
@@ -44,7 +44,7 @@ GeneratorObject::~GeneratorObject()
 void GeneratorObject::visit_edges(Cell::Visitor& visitor)
 {
     Object::visit_edges(visitor);
-    visitor.visit(m_environment_record);
+    visitor.visit(m_environment);
     visitor.visit(m_generating_function);
     if (m_previous_value.is_object())
         visitor.visit(&m_previous_value.as_object());
@@ -107,7 +107,7 @@ Value GeneratorObject::next_impl(VM& vm, GlobalObject& global_object, Optional<V
     }
 
     // Temporarily switch to the captured environment record
-    TemporaryChange change { vm.running_execution_context().lexical_environment, m_environment_record };
+    TemporaryChange change { vm.running_execution_context().lexical_environment, m_environment };
 
     m_previous_value = bytecode_interpreter->run(*m_generating_function->bytecode_executable(), next_block);
 
diff --git a/Userland/Libraries/LibJS/Runtime/GeneratorObject.h b/Userland/Libraries/LibJS/Runtime/GeneratorObject.h
index 498b451c79..b83b627ffe 100644
--- a/Userland/Libraries/LibJS/Runtime/GeneratorObject.h
+++ b/Userland/Libraries/LibJS/Runtime/GeneratorObject.h
@@ -15,7 +15,7 @@ class GeneratorObject final : public Object {
     JS_OBJECT(GeneratorObject, Object);
 
 public:
-    static GeneratorObject* create(GlobalObject&, Value, OrdinaryFunctionObject*, EnvironmentRecord*, Bytecode::RegisterWindow);
+    static GeneratorObject* create(GlobalObject&, Value, OrdinaryFunctionObject*, Environment*, Bytecode::RegisterWindow);
     GeneratorObject(GlobalObject&, Object& prototype);
     virtual void initialize(GlobalObject&) override;
     virtual ~GeneratorObject() override;
@@ -25,7 +25,7 @@ public:
     void set_done() { m_done = true; }
 
 private:
-    EnvironmentRecord* m_environment_record { nullptr };
+    Environment* m_environment { nullptr };
     OrdinaryFunctionObject* m_generating_function { nullptr };
     Value m_previous_value;
     Bytecode::RegisterWindow m_frame;
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalEnvironment.cpp b/Userland/Libraries/LibJS/Runtime/GlobalEnvironment.cpp
new file mode 100644
index 0000000000..4cc7577557
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/GlobalEnvironment.cpp
@@ -0,0 +1,214 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/AST.h>
+#include <LibJS/Runtime/DeclarativeEnvironment.h>
+#include <LibJS/Runtime/GlobalEnvironment.h>
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/ObjectEnvironment.h>
+
+namespace JS {
+
+GlobalEnvironment::GlobalEnvironment(GlobalObject& global_object)
+    : Environment(nullptr)
+{
+    m_object_record = global_object.heap().allocate<ObjectEnvironment>(global_object, global_object, ObjectEnvironment::IsWithEnvironment::No, nullptr);
+    m_declarative_record = global_object.heap().allocate<DeclarativeEnvironment>(global_object);
+}
+
+void GlobalEnvironment::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_object_record);
+    visitor.visit(m_declarative_record);
+}
+
+Optional<Variable> GlobalEnvironment::get_from_environment(FlyString const& name) const
+{
+    // FIXME: This should be a "composite" of the object record and the declarative record.
+    return m_object_record->get_from_environment(name);
+}
+
+void GlobalEnvironment::put_into_environment(FlyString const& name, Variable variable)
+{
+    // FIXME: This should be a "composite" of the object record and the declarative record.
+    m_object_record->put_into_environment(name, variable);
+}
+
+bool GlobalEnvironment::delete_from_environment(FlyString const& name)
+{
+    // FIXME: This should be a "composite" of the object record and the declarative record.
+    return object_record().delete_from_environment(name);
+}
+
+Value GlobalEnvironment::get_this_binding(GlobalObject&) const
+{
+    return &global_object();
+}
+
+Value GlobalEnvironment::global_this_value() const
+{
+    return &global_object();
+}
+
+// 9.1.1.4.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-global-environment-records-hasbinding-n
+bool GlobalEnvironment::has_binding(FlyString const& name) const
+{
+    if (m_declarative_record->has_binding(name))
+        return true;
+    return m_object_record->has_binding(name);
+}
+
+// 9.1.1.4.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-global-environment-records-createmutablebinding-n-d
+void GlobalEnvironment::create_mutable_binding(GlobalObject& global_object, FlyString const& name, bool can_be_deleted)
+{
+    if (m_declarative_record->has_binding(name)) {
+        global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
+        return;
+    }
+    m_declarative_record->create_mutable_binding(global_object, name, can_be_deleted);
+}
+
+// 9.1.1.4.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-global-environment-records-createimmutablebinding-n-s
+void GlobalEnvironment::create_immutable_binding(GlobalObject& global_object, FlyString const& name, bool strict)
+{
+    if (m_declarative_record->has_binding(name)) {
+        global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
+        return;
+    }
+    m_declarative_record->create_immutable_binding(global_object, name, strict);
+}
+
+// 9.1.1.4.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-global-environment-records-initializebinding-n-v
+void GlobalEnvironment::initialize_binding(GlobalObject& global_object, FlyString const& name, Value value)
+{
+    if (m_declarative_record->has_binding(name)) {
+        m_declarative_record->initialize_binding(global_object, name, value);
+        return;
+    }
+    m_object_record->initialize_binding(global_object, name, value);
+}
+
+// 9.1.1.4.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-global-environment-records-setmutablebinding-n-v-s
+void GlobalEnvironment::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
+{
+    if (m_declarative_record->has_binding(name)) {
+        m_declarative_record->set_mutable_binding(global_object, name, value, strict);
+        return;
+    }
+
+    m_object_record->set_mutable_binding(global_object, name, value, strict);
+}
+
+// 9.1.1.4.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-global-environment-records-getbindingvalue-n-s
+Value GlobalEnvironment::get_binding_value(GlobalObject& global_object, FlyString const& name, bool strict)
+{
+    if (m_declarative_record->has_binding(name))
+        return m_declarative_record->get_binding_value(global_object, name, strict);
+    return m_object_record->get_binding_value(global_object, name, strict);
+}
+
+// 9.1.1.4.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-global-environment-records-deletebinding-n
+bool GlobalEnvironment::delete_binding(GlobalObject& global_object, FlyString const& name)
+{
+    if (m_declarative_record->has_binding(name))
+        return m_declarative_record->delete_binding(global_object, name);
+
+    bool existing_prop = m_object_record->binding_object().has_own_property(name);
+    if (existing_prop) {
+        bool status = m_object_record->delete_binding(global_object, name);
+        if (status) {
+            m_var_names.remove_all_matching([&](auto& entry) { return entry == name; });
+        }
+        return status;
+    }
+    return true;
+}
+
+// 9.1.1.4.12 HasVarDeclaration ( N ), https://tc39.es/ecma262/#sec-hasvardeclaration
+bool GlobalEnvironment::has_var_declaration(FlyString const& name) const
+{
+    return m_var_names.contains_slow(name);
+}
+
+// 9.1.1.4.13 HasLexicalDeclaration ( N ), https://tc39.es/ecma262/#sec-haslexicaldeclaration
+bool GlobalEnvironment::has_lexical_declaration(FlyString const& name) const
+{
+    return m_declarative_record->has_binding(name);
+}
+
+// 9.1.1.4.14 HasRestrictedGlobalProperty ( N ), https://tc39.es/ecma262/#sec-hasrestrictedglobalproperty
+bool GlobalEnvironment::has_restricted_global_property(FlyString const& name) const
+{
+    auto existing_prop = m_object_record->binding_object().get_own_property_descriptor(name);
+    if (!existing_prop.has_value() || existing_prop.value().value.is_undefined())
+        return false;
+    if (existing_prop.value().attributes.is_configurable())
+        return false;
+    return true;
+}
+
+// 9.1.1.4.15 CanDeclareGlobalVar ( N ), https://tc39.es/ecma262/#sec-candeclareglobalvar
+bool GlobalEnvironment::can_declare_global_var(FlyString const& name) const
+{
+    bool has_property = m_object_record->binding_object().has_own_property(name);
+    if (has_property)
+        return true;
+    return m_object_record->binding_object().is_extensible();
+}
+
+// 9.1.1.4.16 CanDeclareGlobalFunction ( N ), https://tc39.es/ecma262/#sec-candeclareglobalfunction
+bool GlobalEnvironment::can_declare_global_function(FlyString const& name) const
+{
+    auto existing_prop = m_object_record->binding_object().get_own_property_descriptor(name);
+    if (!existing_prop.has_value() || existing_prop.value().value.is_undefined())
+        return m_object_record->binding_object().is_extensible();
+    if (existing_prop.value().attributes.is_configurable())
+        return true;
+    if (existing_prop.value().is_data_descriptor() && existing_prop.value().attributes.is_writable() && existing_prop.value().attributes.is_enumerable())
+        return true;
+    return false;
+}
+
+// 9.1.1.4.17 CreateGlobalVarBinding ( N, D ), https://tc39.es/ecma262/#sec-createglobalvarbinding
+void GlobalEnvironment::create_global_var_binding(FlyString const& name, bool can_be_deleted)
+{
+    bool has_property = m_object_record->binding_object().has_own_property(name);
+    bool extensible = m_object_record->binding_object().is_extensible();
+    if (!has_property && extensible) {
+        m_object_record->create_mutable_binding(static_cast<GlobalObject&>(m_object_record->binding_object()), name, can_be_deleted);
+        m_object_record->initialize_binding(m_object_record->global_object(), name, js_undefined());
+    }
+    if (!m_var_names.contains_slow(name))
+        m_var_names.append(name);
+}
+
+// 9.1.1.4.18 CreateGlobalFunctionBinding ( N, V, D ), https://tc39.es/ecma262/#sec-createglobalfunctionbinding
+void GlobalEnvironment::create_global_function_binding(FlyString const& name, Value value, bool can_be_deleted)
+{
+    auto existing_prop = m_object_record->binding_object().get_own_property_descriptor(name);
+    PropertyDescriptor desc;
+    if (!existing_prop.has_value() || existing_prop.value().value.is_undefined() || existing_prop.value().attributes.is_configurable()) {
+        desc.value = value;
+        desc.attributes.set_has_writable();
+        desc.attributes.set_writable();
+        desc.attributes.set_has_enumerable();
+        desc.attributes.set_enumerable();
+        desc.attributes.set_has_configurable();
+        if (can_be_deleted)
+            desc.attributes.set_configurable();
+    } else {
+        desc.value = value;
+    }
+    // FIXME: This should be DefinePropertyOrThrow, followed by Set
+    m_object_record->binding_object().define_property(name, value, desc.attributes);
+    if (vm().exception())
+        return;
+    if (!m_var_names.contains_slow(name))
+        m_var_names.append(name);
+}
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalEnvironment.h b/Userland/Libraries/LibJS/Runtime/GlobalEnvironment.h
new file mode 100644
index 0000000000..6876d811d1
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/GlobalEnvironment.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/Environment.h>
+
+namespace JS {
+
+class GlobalEnvironment final : public Environment {
+    JS_ENVIRONMENT(GlobalEnvironment, Environment);
+
+public:
+    explicit GlobalEnvironment(GlobalObject&);
+
+    virtual Optional<Variable> get_from_environment(FlyString const&) const override;
+    virtual void put_into_environment(FlyString const&, Variable) override;
+    virtual bool delete_from_environment(FlyString const&) override;
+    virtual bool has_this_binding() const final { return true; }
+    virtual Value get_this_binding(GlobalObject&) const final;
+
+    virtual bool has_binding(FlyString const& name) const override;
+    virtual void create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
+    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
+    virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
+    virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual bool delete_binding(GlobalObject&, FlyString const& name) override;
+
+    Value global_this_value() const;
+
+    // [[ObjectRecord]]
+    ObjectEnvironment& object_record() { return *m_object_record; }
+
+    // [[DeclarativeRecord]]
+    DeclarativeEnvironment& declarative_record() { return *m_declarative_record; }
+
+    bool has_var_declaration(FlyString const& name) const;
+    bool has_lexical_declaration(FlyString const& name) const;
+    bool has_restricted_global_property(FlyString const& name) const;
+    bool can_declare_global_var(FlyString const& name) const;
+    bool can_declare_global_function(FlyString const& name) const;
+    void create_global_var_binding(FlyString const& name, bool can_be_deleted);
+    void create_global_function_binding(FlyString const& name, Value, bool can_be_deleted);
+
+private:
+    virtual bool is_global_environment() const override { return true; }
+    virtual void visit_edges(Visitor&) override;
+
+    ObjectEnvironment* m_object_record { nullptr };
+    DeclarativeEnvironment* m_declarative_record { nullptr };
+
+    Vector<FlyString> m_var_names;
+};
+
+template<>
+inline bool Environment::fast_is<GlobalEnvironment>() const { return is_global_environment(); }
+}
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.cpp b/Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.cpp
deleted file mode 100644
index 2f33ea30db..0000000000
--- a/Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.cpp
+++ /dev/null
@@ -1,214 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include <LibJS/AST.h>
-#include <LibJS/Runtime/DeclarativeEnvironmentRecord.h>
-#include <LibJS/Runtime/GlobalEnvironmentRecord.h>
-#include <LibJS/Runtime/GlobalObject.h>
-#include <LibJS/Runtime/ObjectEnvironmentRecord.h>
-
-namespace JS {
-
-GlobalEnvironmentRecord::GlobalEnvironmentRecord(GlobalObject& global_object)
-    : EnvironmentRecord(nullptr)
-{
-    m_object_record = global_object.heap().allocate<ObjectEnvironmentRecord>(global_object, global_object, ObjectEnvironmentRecord::IsWithEnvironment::No, nullptr);
-    m_declarative_record = global_object.heap().allocate<DeclarativeEnvironmentRecord>(global_object);
-}
-
-void GlobalEnvironmentRecord::visit_edges(Cell::Visitor& visitor)
-{
-    Base::visit_edges(visitor);
-    visitor.visit(m_object_record);
-    visitor.visit(m_declarative_record);
-}
-
-Optional<Variable> GlobalEnvironmentRecord::get_from_environment_record(FlyString const& name) const
-{
-    // FIXME: This should be a "composite" of the object record and the declarative record.
-    return m_object_record->get_from_environment_record(name);
-}
-
-void GlobalEnvironmentRecord::put_into_environment_record(FlyString const& name, Variable variable)
-{
-    // FIXME: This should be a "composite" of the object record and the declarative record.
-    m_object_record->put_into_environment_record(name, variable);
-}
-
-bool GlobalEnvironmentRecord::delete_from_environment_record(FlyString const& name)
-{
-    // FIXME: This should be a "composite" of the object record and the declarative record.
-    return object_record().delete_from_environment_record(name);
-}
-
-Value GlobalEnvironmentRecord::get_this_binding(GlobalObject&) const
-{
-    return &global_object();
-}
-
-Value GlobalEnvironmentRecord::global_this_value() const
-{
-    return &global_object();
-}
-
-// 9.1.1.4.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-global-environment-records-hasbinding-n
-bool GlobalEnvironmentRecord::has_binding(FlyString const& name) const
-{
-    if (m_declarative_record->has_binding(name))
-        return true;
-    return m_object_record->has_binding(name);
-}
-
-// 9.1.1.4.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-global-environment-records-createmutablebinding-n-d
-void GlobalEnvironmentRecord::create_mutable_binding(GlobalObject& global_object, FlyString const& name, bool can_be_deleted)
-{
-    if (m_declarative_record->has_binding(name)) {
-        global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
-        return;
-    }
-    m_declarative_record->create_mutable_binding(global_object, name, can_be_deleted);
-}
-
-// 9.1.1.4.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-global-environment-records-createimmutablebinding-n-s
-void GlobalEnvironmentRecord::create_immutable_binding(GlobalObject& global_object, FlyString const& name, bool strict)
-{
-    if (m_declarative_record->has_binding(name)) {
-        global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
-        return;
-    }
-    m_declarative_record->create_immutable_binding(global_object, name, strict);
-}
-
-// 9.1.1.4.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-global-environment-records-initializebinding-n-v
-void GlobalEnvironmentRecord::initialize_binding(GlobalObject& global_object, FlyString const& name, Value value)
-{
-    if (m_declarative_record->has_binding(name)) {
-        m_declarative_record->initialize_binding(global_object, name, value);
-        return;
-    }
-    m_object_record->initialize_binding(global_object, name, value);
-}
-
-// 9.1.1.4.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-global-environment-records-setmutablebinding-n-v-s
-void GlobalEnvironmentRecord::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
-{
-    if (m_declarative_record->has_binding(name)) {
-        m_declarative_record->set_mutable_binding(global_object, name, value, strict);
-        return;
-    }
-
-    m_object_record->set_mutable_binding(global_object, name, value, strict);
-}
-
-// 9.1.1.4.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-global-environment-records-getbindingvalue-n-s
-Value GlobalEnvironmentRecord::get_binding_value(GlobalObject& global_object, FlyString const& name, bool strict)
-{
-    if (m_declarative_record->has_binding(name))
-        return m_declarative_record->get_binding_value(global_object, name, strict);
-    return m_object_record->get_binding_value(global_object, name, strict);
-}
-
-// 9.1.1.4.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-global-environment-records-deletebinding-n
-bool GlobalEnvironmentRecord::delete_binding(GlobalObject& global_object, FlyString const& name)
-{
-    if (m_declarative_record->has_binding(name))
-        return m_declarative_record->delete_binding(global_object, name);
-
-    bool existing_prop = m_object_record->binding_object().has_own_property(name);
-    if (existing_prop) {
-        bool status = m_object_record->delete_binding(global_object, name);
-        if (status) {
-            m_var_names.remove_all_matching([&](auto& entry) { return entry == name; });
-        }
-        return status;
-    }
-    return true;
-}
-
-// 9.1.1.4.12 HasVarDeclaration ( N ), https://tc39.es/ecma262/#sec-hasvardeclaration
-bool GlobalEnvironmentRecord::has_var_declaration(FlyString const& name) const
-{
-    return m_var_names.contains_slow(name);
-}
-
-// 9.1.1.4.13 HasLexicalDeclaration ( N ), https://tc39.es/ecma262/#sec-haslexicaldeclaration
-bool GlobalEnvironmentRecord::has_lexical_declaration(FlyString const& name) const
-{
-    return m_declarative_record->has_binding(name);
-}
-
-// 9.1.1.4.14 HasRestrictedGlobalProperty ( N ), https://tc39.es/ecma262/#sec-hasrestrictedglobalproperty
-bool GlobalEnvironmentRecord::has_restricted_global_property(FlyString const& name) const
-{
-    auto existing_prop = m_object_record->binding_object().get_own_property_descriptor(name);
-    if (!existing_prop.has_value() || existing_prop.value().value.is_undefined())
-        return false;
-    if (existing_prop.value().attributes.is_configurable())
-        return false;
-    return true;
-}
-
-// 9.1.1.4.15 CanDeclareGlobalVar ( N ), https://tc39.es/ecma262/#sec-candeclareglobalvar
-bool GlobalEnvironmentRecord::can_declare_global_var(FlyString const& name) const
-{
-    bool has_property = m_object_record->binding_object().has_own_property(name);
-    if (has_property)
-        return true;
-    return m_object_record->binding_object().is_extensible();
-}
-
-// 9.1.1.4.16 CanDeclareGlobalFunction ( N ), https://tc39.es/ecma262/#sec-candeclareglobalfunction
-bool GlobalEnvironmentRecord::can_declare_global_function(FlyString const& name) const
-{
-    auto existing_prop = m_object_record->binding_object().get_own_property_descriptor(name);
-    if (!existing_prop.has_value() || existing_prop.value().value.is_undefined())
-        return m_object_record->binding_object().is_extensible();
-    if (existing_prop.value().attributes.is_configurable())
-        return true;
-    if (existing_prop.value().is_data_descriptor() && existing_prop.value().attributes.is_writable() && existing_prop.value().attributes.is_enumerable())
-        return true;
-    return false;
-}
-
-// 9.1.1.4.17 CreateGlobalVarBinding ( N, D ), https://tc39.es/ecma262/#sec-createglobalvarbinding
-void GlobalEnvironmentRecord::create_global_var_binding(FlyString const& name, bool can_be_deleted)
-{
-    bool has_property = m_object_record->binding_object().has_own_property(name);
-    bool extensible = m_object_record->binding_object().is_extensible();
-    if (!has_property && extensible) {
-        m_object_record->create_mutable_binding(static_cast<GlobalObject&>(m_object_record->binding_object()), name, can_be_deleted);
-        m_object_record->initialize_binding(m_object_record->global_object(), name, js_undefined());
-    }
-    if (!m_var_names.contains_slow(name))
-        m_var_names.append(name);
-}
-
-// 9.1.1.4.18 CreateGlobalFunctionBinding ( N, V, D ), https://tc39.es/ecma262/#sec-createglobalfunctionbinding
-void GlobalEnvironmentRecord::create_global_function_binding(FlyString const& name, Value value, bool can_be_deleted)
-{
-    auto existing_prop = m_object_record->binding_object().get_own_property_descriptor(name);
-    PropertyDescriptor desc;
-    if (!existing_prop.has_value() || existing_prop.value().value.is_undefined() || existing_prop.value().attributes.is_configurable()) {
-        desc.value = value;
-        desc.attributes.set_has_writable();
-        desc.attributes.set_writable();
-        desc.attributes.set_has_enumerable();
-        desc.attributes.set_enumerable();
-        desc.attributes.set_has_configurable();
-        if (can_be_deleted)
-            desc.attributes.set_configurable();
-    } else {
-        desc.value = value;
-    }
-    // FIXME: This should be DefinePropertyOrThrow, followed by Set
-    m_object_record->binding_object().define_property(name, value, desc.attributes);
-    if (vm().exception())
-        return;
-    if (!m_var_names.contains_slow(name))
-        m_var_names.append(name);
-}
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.h b/Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.h
deleted file mode 100644
index 5444176b3b..0000000000
--- a/Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <LibJS/Runtime/EnvironmentRecord.h>
-
-namespace JS {
-
-class GlobalEnvironmentRecord final : public EnvironmentRecord {
-    JS_ENVIRONMENT_RECORD(GlobalEnvironmentRecord, EnvironmentRecord);
-
-public:
-    explicit GlobalEnvironmentRecord(GlobalObject&);
-
-    virtual Optional<Variable> get_from_environment_record(FlyString const&) const override;
-    virtual void put_into_environment_record(FlyString const&, Variable) override;
-    virtual bool delete_from_environment_record(FlyString const&) override;
-    virtual bool has_this_binding() const final { return true; }
-    virtual Value get_this_binding(GlobalObject&) const final;
-
-    virtual bool has_binding(FlyString const& name) const override;
-    virtual void create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
-    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
-    virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
-    virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
-    virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;
-    virtual bool delete_binding(GlobalObject&, FlyString const& name) override;
-
-    Value global_this_value() const;
-
-    // [[ObjectRecord]]
-    ObjectEnvironmentRecord& object_record() { return *m_object_record; }
-
-    // [[DeclarativeRecord]]
-    DeclarativeEnvironmentRecord& declarative_record() { return *m_declarative_record; }
-
-    bool has_var_declaration(FlyString const& name) const;
-    bool has_lexical_declaration(FlyString const& name) const;
-    bool has_restricted_global_property(FlyString const& name) const;
-    bool can_declare_global_var(FlyString const& name) const;
-    bool can_declare_global_function(FlyString const& name) const;
-    void create_global_var_binding(FlyString const& name, bool can_be_deleted);
-    void create_global_function_binding(FlyString const& name, Value, bool can_be_deleted);
-
-private:
-    virtual bool is_global_environment_record() const override { return true; }
-    virtual void visit_edges(Visitor&) override;
-
-    ObjectEnvironmentRecord* m_object_record { nullptr };
-    DeclarativeEnvironmentRecord* m_declarative_record { nullptr };
-
-    Vector<FlyString> m_var_names;
-};
-
-template<>
-inline bool EnvironmentRecord::fast_is<GlobalEnvironmentRecord>() const { return is_global_environment_record(); }
-}
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp b/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
index 62e178c146..81c25365bd 100644
--- a/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
@@ -40,7 +40,7 @@
 #include <LibJS/Runtime/GeneratorFunctionConstructor.h>
 #include <LibJS/Runtime/GeneratorFunctionPrototype.h>
 #include <LibJS/Runtime/GeneratorObjectPrototype.h>
-#include <LibJS/Runtime/GlobalEnvironmentRecord.h>
+#include <LibJS/Runtime/GlobalEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/IteratorPrototype.h>
 #include <LibJS/Runtime/JSONObject.h>
@@ -99,7 +99,7 @@ void GlobalObject::initialize_global_object()
     m_object_prototype = heap().allocate_without_global_object<ObjectPrototype>(*this);
     m_function_prototype = heap().allocate_without_global_object<FunctionPrototype>(*this);
 
-    m_environment_record = heap().allocate<GlobalEnvironmentRecord>(*this, *this);
+    m_environment = heap().allocate<GlobalEnvironment>(*this, *this);
 
     m_new_object_shape = vm.heap().allocate_without_global_object<Shape>(*this);
     m_new_object_shape->set_prototype_without_transition(m_object_prototype);
@@ -225,7 +225,7 @@ void GlobalObject::visit_edges(Visitor& visitor)
     visitor.visit(m_new_ordinary_function_prototype_object_shape);
     visitor.visit(m_proxy_constructor);
     visitor.visit(m_generator_object_prototype);
-    visitor.visit(m_environment_record);
+    visitor.visit(m_environment);
 
 #define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName, ArrayType) \
     visitor.visit(m_##snake_name##_constructor);                                         \
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalObject.h b/Userland/Libraries/LibJS/Runtime/GlobalObject.h
index ec1c5afa4a..6ff199c520 100644
--- a/Userland/Libraries/LibJS/Runtime/GlobalObject.h
+++ b/Userland/Libraries/LibJS/Runtime/GlobalObject.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <LibJS/Heap/Heap.h>
-#include <LibJS/Runtime/EnvironmentRecord.h>
+#include <LibJS/Runtime/Environment.h>
 #include <LibJS/Runtime/VM.h>
 
 namespace JS {
@@ -21,7 +21,7 @@ public:
 
     virtual ~GlobalObject() override;
 
-    GlobalEnvironmentRecord& environment_record() { return *m_environment_record; }
+    GlobalEnvironment& environment() { return *m_environment; }
 
     Console& console() { return *m_console; }
 
@@ -87,7 +87,7 @@ private:
     // Not included in JS_ENUMERATE_NATIVE_OBJECTS due to missing distinct constructor
     GeneratorObjectPrototype* m_generator_object_prototype { nullptr };
 
-    GlobalEnvironmentRecord* m_environment_record { nullptr };
+    GlobalEnvironment* m_environment { nullptr };
 
 #define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName, ArrayType) \
     ConstructorName* m_##snake_name##_constructor { nullptr };                           \
diff --git a/Userland/Libraries/LibJS/Runtime/NativeFunction.cpp b/Userland/Libraries/LibJS/Runtime/NativeFunction.cpp
index c4e32f7812..83cd77f247 100644
--- a/Userland/Libraries/LibJS/Runtime/NativeFunction.cpp
+++ b/Userland/Libraries/LibJS/Runtime/NativeFunction.cpp
@@ -47,7 +47,7 @@ Value NativeFunction::construct(FunctionObject&)
     return {};
 }
 
-FunctionEnvironmentRecord* NativeFunction::create_environment_record(FunctionObject&)
+FunctionEnvironment* NativeFunction::create_environment(FunctionObject&)
 {
     return nullptr;
 }
diff --git a/Userland/Libraries/LibJS/Runtime/NativeFunction.h b/Userland/Libraries/LibJS/Runtime/NativeFunction.h
index 39d66edb76..0f88bcf24d 100644
--- a/Userland/Libraries/LibJS/Runtime/NativeFunction.h
+++ b/Userland/Libraries/LibJS/Runtime/NativeFunction.h
@@ -36,7 +36,7 @@ protected:
     explicit NativeFunction(Object& prototype);
 
 private:
-    virtual FunctionEnvironmentRecord* create_environment_record(FunctionObject&) override final;
+    virtual FunctionEnvironment* create_environment(FunctionObject&) override final;
     virtual bool is_native_function() const final { return true; }
 
     FlyString m_name;
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp b/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp
new file mode 100644
index 0000000000..a2006cb190
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/AST.h>
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/ObjectEnvironment.h>
+
+namespace JS {
+
+ObjectEnvironment::ObjectEnvironment(Object& binding_object, IsWithEnvironment is_with_environment, Environment* outer_environment)
+    : Environment(outer_environment)
+    , m_binding_object(binding_object)
+    , m_with_environment(is_with_environment == IsWithEnvironment::Yes)
+{
+}
+
+void ObjectEnvironment::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(&m_binding_object);
+}
+
+Optional<Variable> ObjectEnvironment::get_from_environment(FlyString const& name) const
+{
+    auto value = m_binding_object.get(name);
+    if (value.is_empty())
+        return {};
+    return Variable { value, DeclarationKind::Var };
+}
+
+void ObjectEnvironment::put_into_environment(FlyString const& name, Variable variable)
+{
+    m_binding_object.put(name, variable.value);
+}
+
+bool ObjectEnvironment::delete_from_environment(FlyString const& name)
+{
+    return m_binding_object.delete_property(name);
+}
+
+// 9.1.1.2.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-object-environment-records-hasbinding-n
+bool ObjectEnvironment::has_binding(FlyString const& name) const
+{
+    bool found_binding = m_binding_object.has_property(name);
+    if (!found_binding)
+        return false;
+
+    // FIXME: Implement the rest of this operation.
+
+    return true;
+}
+
+// 9.1.1.2.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-object-environment-records-createmutablebinding-n-d
+void ObjectEnvironment::create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted)
+{
+    PropertyAttributes attributes;
+    attributes.set_enumerable();
+    attributes.set_has_enumerable();
+    attributes.set_writable();
+    attributes.set_has_writable();
+    attributes.set_has_configurable();
+    if (can_be_deleted)
+        attributes.set_configurable();
+    m_binding_object.define_property(name, js_undefined(), attributes, true);
+}
+
+// 9.1.1.2.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-createimmutablebinding-n-s
+void ObjectEnvironment::create_immutable_binding(GlobalObject&, FlyString const&, bool)
+{
+    // "The CreateImmutableBinding concrete method of an object Environment Record is never used within this specification."
+    VERIFY_NOT_REACHED();
+}
+
+// 9.1.1.2.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-object-environment-records-initializebinding-n-v
+void ObjectEnvironment::initialize_binding(GlobalObject& global_object, FlyString const& name, Value value)
+{
+    set_mutable_binding(global_object, name, value, false);
+}
+
+// 9.1.1.2.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-object-environment-records-setmutablebinding-n-v-s
+void ObjectEnvironment::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
+{
+    bool still_exists = m_binding_object.has_property(name);
+    if (!still_exists && strict) {
+        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
+        return;
+    }
+    // FIXME: This should use the Set abstract operation.
+    // FIXME: Set returns a bool, so this may need to return a bool as well.
+    m_binding_object.put(name, value);
+}
+
+// 9.1.1.2.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-getbindingvalue-n-s
+Value ObjectEnvironment::get_binding_value(GlobalObject& global_object, FlyString const& name, bool strict)
+{
+    if (!m_binding_object.has_property(name)) {
+        if (!strict)
+            return js_undefined();
+
+        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
+        return {};
+    }
+    // FIXME: This should use the Get abstract operation.
+    return m_binding_object.get(name);
+}
+
+// 9.1.1.2.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-object-environment-records-deletebinding-n
+bool ObjectEnvironment::delete_binding(GlobalObject&, FlyString const& name)
+{
+    return m_binding_object.delete_property(name);
+}
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.h b/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.h
new file mode 100644
index 0000000000..46d4aa2dcf
--- /dev/null
+++ b/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/Environment.h>
+
+namespace JS {
+
+class ObjectEnvironment : public Environment {
+    JS_ENVIRONMENT(ObjectEnvironment, Environment);
+
+public:
+    enum class IsWithEnvironment {
+        No,
+        Yes,
+    };
+    ObjectEnvironment(Object& binding_object, IsWithEnvironment, Environment* outer_environment);
+
+    virtual Optional<Variable> get_from_environment(FlyString const&) const override;
+    virtual void put_into_environment(FlyString const&, Variable) override;
+    virtual bool delete_from_environment(FlyString const&) override;
+
+    virtual bool has_binding(FlyString const& name) const override;
+    virtual void create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
+    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
+    virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
+    virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual bool delete_binding(GlobalObject&, FlyString const& name) override;
+
+    // 9.1.1.2.10 WithBaseObject ( ), https://tc39.es/ecma262/#sec-object-environment-records-withbaseobject
+    virtual Object* with_base_object() const override
+    {
+        if (is_with_environment())
+            return &m_binding_object;
+        return nullptr;
+    }
+
+    // [[BindingObject]], The binding object of this Environment Record.
+    Object& binding_object() { return m_binding_object; }
+
+    // [[IsWithEnvironment]], Indicates whether this Environment Record is created for a with statement.
+    bool is_with_environment() const { return m_with_environment; }
+
+private:
+    virtual void visit_edges(Visitor&) override;
+
+    Object& m_binding_object;
+    bool m_with_environment { false };
+};
+
+}
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.cpp b/Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.cpp
deleted file mode 100644
index c0ee297ad5..0000000000
--- a/Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.cpp
+++ /dev/null
@@ -1,116 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include <LibJS/AST.h>
-#include <LibJS/Runtime/GlobalObject.h>
-#include <LibJS/Runtime/ObjectEnvironmentRecord.h>
-
-namespace JS {
-
-ObjectEnvironmentRecord::ObjectEnvironmentRecord(Object& binding_object, IsWithEnvironment is_with_environment, EnvironmentRecord* outer_environment)
-    : EnvironmentRecord(outer_environment)
-    , m_binding_object(binding_object)
-    , m_with_environment(is_with_environment == IsWithEnvironment::Yes)
-{
-}
-
-void ObjectEnvironmentRecord::visit_edges(Cell::Visitor& visitor)
-{
-    Base::visit_edges(visitor);
-    visitor.visit(&m_binding_object);
-}
-
-Optional<Variable> ObjectEnvironmentRecord::get_from_environment_record(FlyString const& name) const
-{
-    auto value = m_binding_object.get(name);
-    if (value.is_empty())
-        return {};
-    return Variable { value, DeclarationKind::Var };
-}
-
-void ObjectEnvironmentRecord::put_into_environment_record(FlyString const& name, Variable variable)
-{
-    m_binding_object.put(name, variable.value);
-}
-
-bool ObjectEnvironmentRecord::delete_from_environment_record(FlyString const& name)
-{
-    return m_binding_object.delete_property(name);
-}
-
-// 9.1.1.2.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-object-environment-records-hasbinding-n
-bool ObjectEnvironmentRecord::has_binding(FlyString const& name) const
-{
-    bool found_binding = m_binding_object.has_property(name);
-    if (!found_binding)
-        return false;
-
-    // FIXME: Implement the rest of this operation.
-
-    return true;
-}
-
-// 9.1.1.2.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-object-environment-records-createmutablebinding-n-d
-void ObjectEnvironmentRecord::create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted)
-{
-    PropertyAttributes attributes;
-    attributes.set_enumerable();
-    attributes.set_has_enumerable();
-    attributes.set_writable();
-    attributes.set_has_writable();
-    attributes.set_has_configurable();
-    if (can_be_deleted)
-        attributes.set_configurable();
-    m_binding_object.define_property(name, js_undefined(), attributes, true);
-}
-
-// 9.1.1.2.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-createimmutablebinding-n-s
-void ObjectEnvironmentRecord::create_immutable_binding(GlobalObject&, FlyString const&, bool)
-{
-    // "The CreateImmutableBinding concrete method of an object Environment Record is never used within this specification."
-    VERIFY_NOT_REACHED();
-}
-
-// 9.1.1.2.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-object-environment-records-initializebinding-n-v
-void ObjectEnvironmentRecord::initialize_binding(GlobalObject& global_object, FlyString const& name, Value value)
-{
-    set_mutable_binding(global_object, name, value, false);
-}
-
-// 9.1.1.2.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-object-environment-records-setmutablebinding-n-v-s
-void ObjectEnvironmentRecord::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
-{
-    bool still_exists = m_binding_object.has_property(name);
-    if (!still_exists && strict) {
-        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
-        return;
-    }
-    // FIXME: This should use the Set abstract operation.
-    // FIXME: Set returns a bool, so this may need to return a bool as well.
-    m_binding_object.put(name, value);
-}
-
-// 9.1.1.2.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-getbindingvalue-n-s
-Value ObjectEnvironmentRecord::get_binding_value(GlobalObject& global_object, FlyString const& name, bool strict)
-{
-    if (!m_binding_object.has_property(name)) {
-        if (!strict)
-            return js_undefined();
-
-        global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
-        return {};
-    }
-    // FIXME: This should use the Get abstract operation.
-    return m_binding_object.get(name);
-}
-
-// 9.1.1.2.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-object-environment-records-deletebinding-n
-bool ObjectEnvironmentRecord::delete_binding(GlobalObject&, FlyString const& name)
-{
-    return m_binding_object.delete_property(name);
-}
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.h b/Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.h
deleted file mode 100644
index 57a8f82d0b..0000000000
--- a/Userland/Libraries/LibJS/Runtime/ObjectEnvironmentRecord.h
+++ /dev/null
@@ -1,56 +0,0 @@
-/*
- * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <LibJS/Runtime/EnvironmentRecord.h>
-
-namespace JS {
-
-class ObjectEnvironmentRecord : public EnvironmentRecord {
-    JS_ENVIRONMENT_RECORD(ObjectEnvironmentRecord, EnvironmentRecord);
-
-public:
-    enum class IsWithEnvironment {
-        No,
-        Yes,
-    };
-    ObjectEnvironmentRecord(Object& binding_object, IsWithEnvironment, EnvironmentRecord* outer_environment);
-
-    virtual Optional<Variable> get_from_environment_record(FlyString const&) const override;
-    virtual void put_into_environment_record(FlyString const&, Variable) override;
-    virtual bool delete_from_environment_record(FlyString const&) override;
-
-    virtual bool has_binding(FlyString const& name) const override;
-    virtual void create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
-    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
-    virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
-    virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
-    virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;
-    virtual bool delete_binding(GlobalObject&, FlyString const& name) override;
-
-    // 9.1.1.2.10 WithBaseObject ( ), https://tc39.es/ecma262/#sec-object-environment-records-withbaseobject
-    virtual Object* with_base_object() const override
-    {
-        if (is_with_environment())
-            return &m_binding_object;
-        return nullptr;
-    }
-
-    // [[BindingObject]], The binding object of this Environment Record.
-    Object& binding_object() { return m_binding_object; }
-
-    // [[IsWithEnvironment]], Indicates whether this Environment Record is created for a with statement.
-    bool is_with_environment() const { return m_with_environment; }
-
-private:
-    virtual void visit_edges(Visitor&) override;
-
-    Object& m_binding_object;
-    bool m_with_environment { false };
-};
-
-}
diff --git a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp
index 0c01c16fcc..5e900f6125 100644
--- a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp
@@ -14,7 +14,7 @@
 #include <LibJS/Interpreter.h>
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/Error.h>
-#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
+#include <LibJS/Runtime/FunctionEnvironment.h>
 #include <LibJS/Runtime/GeneratorObject.h>
 #include <LibJS/Runtime/GeneratorObjectPrototype.h>
 #include <LibJS/Runtime/GlobalObject.h>
@@ -36,7 +36,7 @@ static OrdinaryFunctionObject* typed_this(VM& vm, GlobalObject& global_object)
     return static_cast<OrdinaryFunctionObject*>(this_object);
 }
 
-OrdinaryFunctionObject* OrdinaryFunctionObject::create(GlobalObject& global_object, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 m_function_length, EnvironmentRecord* parent_scope, FunctionKind kind, bool is_strict, bool is_arrow_function)
+OrdinaryFunctionObject* OrdinaryFunctionObject::create(GlobalObject& global_object, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 m_function_length, Environment* parent_scope, FunctionKind kind, bool is_strict, bool is_arrow_function)
 {
     Object* prototype = nullptr;
     switch (kind) {
@@ -50,7 +50,7 @@ OrdinaryFunctionObject* OrdinaryFunctionObject::create(GlobalObject& global_obje
     return global_object.heap().allocate<OrdinaryFunctionObject>(global_object, global_object, name, body, move(parameters), m_function_length, parent_scope, *prototype, kind, is_strict, is_arrow_function);
 }
 
-OrdinaryFunctionObject::OrdinaryFunctionObject(GlobalObject& global_object, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 function_length, EnvironmentRecord* parent_scope, Object& prototype, FunctionKind kind, bool is_strict, bool is_arrow_function)
+OrdinaryFunctionObject::OrdinaryFunctionObject(GlobalObject& global_object, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 function_length, Environment* parent_scope, Object& prototype, FunctionKind kind, bool is_strict, bool is_arrow_function)
     : FunctionObject(is_arrow_function ? vm().this_value(global_object) : Value(), {}, prototype)
     , m_name(name)
     , m_body(body)
@@ -113,7 +113,7 @@ void OrdinaryFunctionObject::visit_edges(Visitor& visitor)
     visitor.visit(m_environment);
 }
 
-FunctionEnvironmentRecord* OrdinaryFunctionObject::create_environment_record(FunctionObject& function_being_invoked)
+FunctionEnvironment* OrdinaryFunctionObject::create_environment(FunctionObject& function_being_invoked)
 {
     HashMap<FlyString, Variable> variables;
     for (auto& parameter : m_parameters) {
@@ -142,11 +142,11 @@ FunctionEnvironmentRecord* OrdinaryFunctionObject::create_environment_record(Fun
         }
     }
 
-    auto* environment = heap().allocate<FunctionEnvironmentRecord>(global_object(), m_environment, variables);
+    auto* environment = heap().allocate<FunctionEnvironment>(global_object(), m_environment, variables);
     environment->set_function_object(function_being_invoked);
     if (m_is_arrow_function) {
-        if (is<FunctionEnvironmentRecord>(m_environment))
-            environment->set_new_target(static_cast<FunctionEnvironmentRecord*>(m_environment)->new_target());
+        if (is<FunctionEnvironment>(m_environment))
+            environment->set_new_target(static_cast<FunctionEnvironment*>(m_environment)->new_target());
     }
     return environment;
 }
diff --git a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h
index 5720c87845..721c404c6e 100644
--- a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h
+++ b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h
@@ -16,9 +16,9 @@ class OrdinaryFunctionObject final : public FunctionObject {
     JS_OBJECT(OrdinaryFunctionObject, FunctionObject);
 
 public:
-    static OrdinaryFunctionObject* create(GlobalObject&, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 m_function_length, EnvironmentRecord* parent_scope, FunctionKind, bool is_strict, bool is_arrow_function = false);
+    static OrdinaryFunctionObject* create(GlobalObject&, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 m_function_length, Environment* parent_scope, FunctionKind, bool is_strict, bool is_arrow_function = false);
 
-    OrdinaryFunctionObject(GlobalObject&, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 m_function_length, EnvironmentRecord* parent_scope, Object& prototype, FunctionKind, bool is_strict, bool is_arrow_function = false);
+    OrdinaryFunctionObject(GlobalObject&, const FlyString& name, const Statement& body, Vector<FunctionNode::Parameter> parameters, i32 m_function_length, Environment* parent_scope, Object& prototype, FunctionKind, bool is_strict, bool is_arrow_function = false);
     virtual void initialize(GlobalObject&) override;
     virtual ~OrdinaryFunctionObject();
 
@@ -35,7 +35,7 @@ public:
 
     auto& bytecode_executable() const { return m_bytecode_executable; }
 
-    virtual EnvironmentRecord* environment() override { return m_environment; }
+    virtual Environment* environment() override { return m_environment; }
 
     GlobalObject* realm() const override { return m_realm; }
 
@@ -44,7 +44,7 @@ protected:
 
 private:
     virtual bool is_ordinary_function_object() const override { return true; }
-    virtual FunctionEnvironmentRecord* create_environment_record(FunctionObject&) override;
+    virtual FunctionEnvironment* create_environment(FunctionObject&) override;
     virtual void visit_edges(Visitor&) override;
 
     Value execute_function_body();
@@ -56,7 +56,7 @@ private:
     NonnullRefPtr<Statement> m_body;
     const Vector<FunctionNode::Parameter> m_parameters;
     Optional<Bytecode::Executable> m_bytecode_executable;
-    EnvironmentRecord* m_environment { nullptr };
+    Environment* m_environment { nullptr };
     GlobalObject* m_realm { nullptr };
     i32 m_function_length { 0 };
     FunctionKind m_kind { FunctionKind::Regular };
diff --git a/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp b/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp
index bc2f4abb27..6e7d791030 100644
--- a/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp
@@ -478,10 +478,10 @@ const FlyString& ProxyObject::name() const
     return static_cast<FunctionObject&>(m_target).name();
 }
 
-FunctionEnvironmentRecord* ProxyObject::create_environment_record(FunctionObject& function_being_invoked)
+FunctionEnvironment* ProxyObject::create_environment(FunctionObject& function_being_invoked)
 {
     VERIFY(is_function());
-    return static_cast<FunctionObject&>(m_target).create_environment_record(function_being_invoked);
+    return static_cast<FunctionObject&>(m_target).create_environment(function_being_invoked);
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/ProxyObject.h b/Userland/Libraries/LibJS/Runtime/ProxyObject.h
index 566310aea9..da89558591 100644
--- a/Userland/Libraries/LibJS/Runtime/ProxyObject.h
+++ b/Userland/Libraries/LibJS/Runtime/ProxyObject.h
@@ -22,7 +22,7 @@ public:
     virtual Value call() override;
     virtual Value construct(FunctionObject& new_target) override;
     virtual const FlyString& name() const override;
-    virtual FunctionEnvironmentRecord* create_environment_record(FunctionObject&) override;
+    virtual FunctionEnvironment* create_environment(FunctionObject&) override;
 
     const Object& target() const { return m_target; }
     const Object& handler() const { return m_handler; }
diff --git a/Userland/Libraries/LibJS/Runtime/Reference.cpp b/Userland/Libraries/LibJS/Runtime/Reference.cpp
index 06160498f6..4e3265ce0d 100644
--- a/Userland/Libraries/LibJS/Runtime/Reference.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Reference.cpp
@@ -47,8 +47,8 @@ void Reference::put_value(GlobalObject& global_object, Value value)
         return;
     }
 
-    VERIFY(m_base_type == BaseType::EnvironmentRecord);
-    auto existing_variable = m_base_environment_record->get_from_environment_record(m_name.as_string());
+    VERIFY(m_base_type == BaseType::Environment);
+    auto existing_variable = m_base_environment->get_from_environment(m_name.as_string());
     Variable variable {
         .value = value,
         .declaration_kind = existing_variable.has_value() ? existing_variable->declaration_kind : DeclarationKind::Var
@@ -60,7 +60,7 @@ void Reference::put_value(GlobalObject& global_object, Value value)
         return;
     }
 
-    m_base_environment_record->put_into_environment_record(m_name.as_string(), variable);
+    m_base_environment->put_into_environment(m_name.as_string(), variable);
 }
 
 void Reference::throw_reference_error(GlobalObject& global_object)
@@ -87,8 +87,8 @@ Value Reference::get_value(GlobalObject& global_object, bool throw_if_undefined)
         return base_obj->get(m_name).value_or(js_undefined());
     }
 
-    VERIFY(m_base_type == BaseType::EnvironmentRecord);
-    auto value = m_base_environment_record->get_from_environment_record(m_name.as_string());
+    VERIFY(m_base_type == BaseType::Environment);
+    auto value = m_base_environment->get_from_environment(m_name.as_string());
     if (!value.has_value()) {
         if (!throw_if_undefined) {
             // FIXME: This is an ad-hoc hack for the `typeof` operator until we support proper variable bindings.
@@ -121,8 +121,8 @@ bool Reference::delete_(GlobalObject& global_object)
         return succeeded;
     }
 
-    VERIFY(m_base_type == BaseType::EnvironmentRecord);
-    return m_base_environment_record->delete_from_environment_record(m_name.as_string());
+    VERIFY(m_base_type == BaseType::Environment);
+    return m_base_environment->delete_from_environment(m_name.as_string());
 }
 
 String Reference::to_string() const
@@ -133,7 +133,7 @@ String Reference::to_string() const
     case BaseType::Unresolvable:
         builder.append("Unresolvable");
         break;
-    case BaseType::EnvironmentRecord:
+    case BaseType::Environment:
         builder.appendff("{}", base_environment().class_name());
         break;
     case BaseType::Value:
diff --git a/Userland/Libraries/LibJS/Runtime/Reference.h b/Userland/Libraries/LibJS/Runtime/Reference.h
index d2df5e06b8..164fca6670 100644
--- a/Userland/Libraries/LibJS/Runtime/Reference.h
+++ b/Userland/Libraries/LibJS/Runtime/Reference.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/String.h>
-#include <LibJS/Runtime/EnvironmentRecord.h>
+#include <LibJS/Runtime/Environment.h>
 #include <LibJS/Runtime/PropertyName.h>
 #include <LibJS/Runtime/Value.h>
 
@@ -18,7 +18,7 @@ public:
     enum class BaseType : u8 {
         Unresolvable,
         Value,
-        EnvironmentRecord,
+        Environment,
     };
 
     Reference() { }
@@ -44,9 +44,9 @@ public:
         }
     }
 
-    Reference(EnvironmentRecord& base, FlyString const& referenced_name, bool strict = false)
-        : m_base_type(BaseType::EnvironmentRecord)
-        , m_base_environment_record(&base)
+    Reference(Environment& base, FlyString const& referenced_name, bool strict = false)
+        : m_base_type(BaseType::Environment)
+        , m_base_environment(&base)
         , m_name(referenced_name)
         , m_strict(strict)
     {
@@ -58,10 +58,10 @@ public:
         return m_base_value;
     }
 
-    EnvironmentRecord& base_environment() const
+    Environment& base_environment() const
     {
-        VERIFY(m_base_type == BaseType::EnvironmentRecord);
-        return *m_base_environment_record;
+        VERIFY(m_base_type == BaseType::Environment);
+        return *m_base_environment;
     }
 
     PropertyName const& name() const { return m_name; }
@@ -75,7 +75,7 @@ public:
     {
         if (is_unresolvable())
             return false;
-        if (m_base_type == BaseType::EnvironmentRecord)
+        if (m_base_type == BaseType::Environment)
             return false;
         if (m_base_value.is_boolean() || m_base_value.is_string() || m_base_value.is_symbol() || m_base_value.is_bigint() || m_base_value.is_number() || m_base_value.is_object())
             return true;
@@ -109,7 +109,7 @@ private:
     BaseType m_base_type { BaseType::Unresolvable };
     union {
         Value m_base_value {};
-        EnvironmentRecord* m_base_environment_record;
+        Environment* m_base_environment;
     };
     PropertyName m_name;
     Value m_this_value;
diff --git a/Userland/Libraries/LibJS/Runtime/VM.cpp b/Userland/Libraries/LibJS/Runtime/VM.cpp
index f79c8c6085..48877aa0a1 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.cpp
+++ b/Userland/Libraries/LibJS/Runtime/VM.cpp
@@ -13,8 +13,8 @@
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/Error.h>
 #include <LibJS/Runtime/FinalizationRegistry.h>
-#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
-#include <LibJS/Runtime/GlobalEnvironmentRecord.h>
+#include <LibJS/Runtime/FunctionEnvironment.h>
+#include <LibJS/Runtime/GlobalEnvironment.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/IteratorOperations.h>
 #include <LibJS/Runtime/NativeFunction.h>
@@ -132,14 +132,14 @@ Symbol* VM::get_global_symbol(const String& description)
     return new_global_symbol;
 }
 
-void VM::set_variable(const FlyString& name, Value value, GlobalObject& global_object, bool first_assignment, EnvironmentRecord* specific_scope)
+void VM::set_variable(const FlyString& name, Value value, GlobalObject& global_object, bool first_assignment, Environment* specific_scope)
 {
     Optional<Variable> possible_match;
     if (!specific_scope && m_execution_context_stack.size()) {
-        for (auto* environment_record = lexical_environment(); environment_record; environment_record = environment_record->outer_environment()) {
-            possible_match = environment_record->get_from_environment_record(name);
+        for (auto* environment = lexical_environment(); environment; environment = environment->outer_environment()) {
+            possible_match = environment->get_from_environment(name);
             if (possible_match.has_value()) {
-                specific_scope = environment_record;
+                specific_scope = environment;
                 break;
             }
         }
@@ -151,12 +151,12 @@ void VM::set_variable(const FlyString& name, Value value, GlobalObject& global_o
             return;
         }
 
-        specific_scope->put_into_environment_record(name, { value, possible_match.value().declaration_kind });
+        specific_scope->put_into_environment(name, { value, possible_match.value().declaration_kind });
         return;
     }
 
     if (specific_scope) {
-        specific_scope->put_into_environment_record(name, { value, DeclarationKind::Var });
+        specific_scope->put_into_environment(name, { value, DeclarationKind::Var });
         return;
     }
 
@@ -165,13 +165,13 @@ void VM::set_variable(const FlyString& name, Value value, GlobalObject& global_o
 
 bool VM::delete_variable(FlyString const& name)
 {
-    EnvironmentRecord* specific_scope = nullptr;
+    Environment* specific_scope = nullptr;
     Optional<Variable> possible_match;
     if (!m_execution_context_stack.is_empty()) {
-        for (auto* environment_record = lexical_environment(); environment_record; environment_record = environment_record->outer_environment()) {
-            possible_match = environment_record->get_from_environment_record(name);
+        for (auto* environment = lexical_environment(); environment; environment = environment->outer_environment()) {
+            possible_match = environment->get_from_environment(name);
             if (possible_match.has_value()) {
-                specific_scope = environment_record;
+                specific_scope = environment;
                 break;
             }
         }
@@ -183,15 +183,15 @@ bool VM::delete_variable(FlyString const& name)
         return false;
 
     VERIFY(specific_scope);
-    return specific_scope->delete_from_environment_record(name);
+    return specific_scope->delete_from_environment(name);
 }
 
-void VM::assign(const FlyString& target, Value value, GlobalObject& global_object, bool first_assignment, EnvironmentRecord* specific_scope)
+void VM::assign(const FlyString& target, Value value, GlobalObject& global_object, bool first_assignment, Environment* specific_scope)
 {
     set_variable(target, move(value), global_object, first_assignment, specific_scope);
 }
 
-void VM::assign(const Variant<NonnullRefPtr<Identifier>, NonnullRefPtr<BindingPattern>>& target, Value value, GlobalObject& global_object, bool first_assignment, EnvironmentRecord* specific_scope)
+void VM::assign(const Variant<NonnullRefPtr<Identifier>, NonnullRefPtr<BindingPattern>>& target, Value value, GlobalObject& global_object, bool first_assignment, Environment* specific_scope)
 {
     if (auto id_ptr = target.get_pointer<NonnullRefPtr<Identifier>>())
         return assign((*id_ptr)->string(), move(value), global_object, first_assignment, specific_scope);
@@ -199,7 +199,7 @@ void VM::assign(const Variant<NonnullRefPtr<Identifier>, NonnullRefPtr<BindingPa
     assign(target.get<NonnullRefPtr<BindingPattern>>(), move(value), global_object, first_assignment, specific_scope);
 }
 
-void VM::assign(const NonnullRefPtr<BindingPattern>& target, Value value, GlobalObject& global_object, bool first_assignment, EnvironmentRecord* specific_scope)
+void VM::assign(const NonnullRefPtr<BindingPattern>& target, Value value, GlobalObject& global_object, bool first_assignment, Environment* specific_scope)
 {
     auto& binding = *target;
 
@@ -365,7 +365,7 @@ Value VM::get_variable(const FlyString& name, GlobalObject& global_object)
             //       a function parameter, or by a local var declaration, we use that.
             //       Otherwise, we return a lazily constructed Array with all the argument values.
             // FIXME: Do something much more spec-compliant.
-            auto possible_match = lexical_environment()->get_from_environment_record(name);
+            auto possible_match = lexical_environment()->get_from_environment(name);
             if (possible_match.has_value())
                 return possible_match.value().value;
             if (!context.arguments_object) {
@@ -378,8 +378,8 @@ Value VM::get_variable(const FlyString& name, GlobalObject& global_object)
             return context.arguments_object;
         }
 
-        for (auto* environment_record = lexical_environment(); environment_record; environment_record = environment_record->outer_environment()) {
-            auto possible_match = environment_record->get_from_environment_record(name);
+        for (auto* environment = lexical_environment(); environment; environment = environment->outer_environment()) {
+            auto possible_match = environment->get_from_environment(name);
             if (exception())
                 return {};
             if (possible_match.has_value())
@@ -393,16 +393,16 @@ Value VM::get_variable(const FlyString& name, GlobalObject& global_object)
 }
 
 // 9.4.2 ResolveBinding ( name [ , env ] ), https://tc39.es/ecma262/#sec-resolvebinding
-Reference VM::resolve_binding(GlobalObject& global_object, FlyString const& name, EnvironmentRecord*)
+Reference VM::resolve_binding(GlobalObject& global_object, FlyString const& name, Environment*)
 {
     // FIXME: This implementation of ResolveBinding is non-conforming.
 
-    for (auto* environment_record = lexical_environment(); environment_record && environment_record->outer_environment(); environment_record = environment_record->outer_environment()) {
-        auto possible_match = environment_record->get_from_environment_record(name);
+    for (auto* environment = lexical_environment(); environment && environment->outer_environment(); environment = environment->outer_environment()) {
+        auto possible_match = environment->get_from_environment(name);
         if (possible_match.has_value())
-            return Reference { *environment_record, name };
+            return Reference { *environment, name };
     }
-    return Reference { global_object.environment_record(), name };
+    return Reference { global_object.environment(), name };
 }
 
 Value VM::construct(FunctionObject& function, FunctionObject& new_target, Optional<MarkedValueList> arguments)
@@ -433,7 +433,7 @@ Value VM::construct(FunctionObject& function, FunctionObject& new_target, Option
     callee_context.arguments = function.bound_arguments();
     if (arguments.has_value())
         callee_context.arguments.extend(arguments.value().values());
-    auto* environment = function.create_environment_record(function);
+    auto* environment = function.create_environment(function);
     callee_context.lexical_environment = environment;
     callee_context.variable_environment = environment;
     if (environment) {
@@ -459,7 +459,7 @@ Value VM::construct(FunctionObject& function, FunctionObject& new_target, Option
     // set the prototype on objects created by constructors that return an object (i.e. NativeFunction subclasses).
     if (function.constructor_kind() == FunctionObject::ConstructorKind::Base && new_target.constructor_kind() == FunctionObject::ConstructorKind::Derived && result.is_object()) {
         if (environment) {
-            verify_cast<FunctionEnvironmentRecord>(lexical_environment())->replace_this_binding(result);
+            verify_cast<FunctionEnvironment>(lexical_environment())->replace_this_binding(result);
         }
         auto prototype = new_target.get(names.prototype);
         if (exception())
@@ -508,7 +508,7 @@ String VM::join_arguments(size_t start_index) const
 Value VM::get_new_target()
 {
     auto& env = get_this_environment(*this);
-    return verify_cast<FunctionEnvironmentRecord>(env).new_target();
+    return verify_cast<FunctionEnvironment>(env).new_target();
 }
 
 Value VM::call_internal(FunctionObject& function, Value this_value, Optional<MarkedValueList> arguments)
@@ -526,12 +526,12 @@ Value VM::call_internal(FunctionObject& function, Value this_value, Optional<Mar
     callee_context.arguments = function.bound_arguments();
     if (arguments.has_value())
         callee_context.arguments.extend(arguments.value().values());
-    auto* environment = function.create_environment_record(function);
+    auto* environment = function.create_environment(function);
     callee_context.lexical_environment = environment;
     callee_context.variable_environment = environment;
 
     if (environment) {
-        VERIFY(environment->this_binding_status() == FunctionEnvironmentRecord::ThisBindingStatus::Uninitialized);
+        VERIFY(environment->this_binding_status() == FunctionEnvironment::ThisBindingStatus::Uninitialized);
         environment->bind_this_value(function.global_object(), callee_context.this_value);
     }
 
@@ -613,13 +613,13 @@ void VM::dump_backtrace() const
         dbgln("-> {}", m_execution_context_stack[i]->function_name);
 }
 
-void VM::dump_environment_record_chain() const
+void VM::dump_environment_chain() const
 {
-    for (auto* environment_record = lexical_environment(); environment_record; environment_record = environment_record->outer_environment()) {
-        dbgln("+> {} ({:p})", environment_record->class_name(), environment_record);
-        if (is<DeclarativeEnvironmentRecord>(*environment_record)) {
-            auto& declarative_environment_record = static_cast<DeclarativeEnvironmentRecord const&>(*environment_record);
-            for (auto& variable : declarative_environment_record.variables()) {
+    for (auto* environment = lexical_environment(); environment; environment = environment->outer_environment()) {
+        dbgln("+> {} ({:p})", environment->class_name(), environment);
+        if (is<DeclarativeEnvironment>(*environment)) {
+            auto& declarative_environment = static_cast<DeclarativeEnvironment const&>(*environment);
+            for (auto& variable : declarative_environment.variables()) {
                 dbgln("    {}", variable.key);
             }
         }
diff --git a/Userland/Libraries/LibJS/Runtime/VM.h b/Userland/Libraries/LibJS/Runtime/VM.h
index d70900407f..0cad90aeba 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.h
+++ b/Userland/Libraries/LibJS/Runtime/VM.h
@@ -49,8 +49,8 @@ struct ExecutionContext {
     Value this_value;
     Vector<Value> arguments;
     Object* arguments_object { nullptr };
-    EnvironmentRecord* lexical_environment { nullptr };
-    EnvironmentRecord* variable_environment { nullptr };
+    Environment* lexical_environment { nullptr };
+    Environment* variable_environment { nullptr };
     bool is_strict_mode { false };
 };
 
@@ -73,7 +73,7 @@ public:
     void clear_exception() { m_exception = nullptr; }
 
     void dump_backtrace() const;
-    void dump_environment_record_chain() const;
+    void dump_environment_chain() const;
 
     class InterpreterExecutionScope {
     public:
@@ -123,11 +123,11 @@ public:
     Vector<ExecutionContext*> const& execution_context_stack() const { return m_execution_context_stack; }
     Vector<ExecutionContext*>& execution_context_stack() { return m_execution_context_stack; }
 
-    EnvironmentRecord const* lexical_environment() const { return running_execution_context().lexical_environment; }
-    EnvironmentRecord* lexical_environment() { return running_execution_context().lexical_environment; }
+    Environment const* lexical_environment() const { return running_execution_context().lexical_environment; }
+    Environment* lexical_environment() { return running_execution_context().lexical_environment; }
 
-    EnvironmentRecord const* variable_environment() const { return running_execution_context().variable_environment; }
-    EnvironmentRecord* variable_environment() { return running_execution_context().variable_environment; }
+    Environment const* variable_environment() const { return running_execution_context().variable_environment; }
+    Environment* variable_environment() { return running_execution_context().variable_environment; }
 
     bool in_strict_mode() const;
 
@@ -198,13 +198,13 @@ public:
     FlyString unwind_until_label() const { return m_unwind_until_label; }
 
     Value get_variable(const FlyString& name, GlobalObject&);
-    void set_variable(const FlyString& name, Value, GlobalObject&, bool first_assignment = false, EnvironmentRecord* specific_scope = nullptr);
+    void set_variable(const FlyString& name, Value, GlobalObject&, bool first_assignment = false, Environment* specific_scope = nullptr);
     bool delete_variable(FlyString const& name);
-    void assign(const Variant<NonnullRefPtr<Identifier>, NonnullRefPtr<BindingPattern>>& target, Value, GlobalObject&, bool first_assignment = false, EnvironmentRecord* specific_scope = nullptr);
-    void assign(const FlyString& target, Value, GlobalObject&, bool first_assignment = false, EnvironmentRecord* specific_scope = nullptr);
-    void assign(const NonnullRefPtr<BindingPattern>& target, Value, GlobalObject&, bool first_assignment = false, EnvironmentRecord* specific_scope = nullptr);
+    void assign(const Variant<NonnullRefPtr<Identifier>, NonnullRefPtr<BindingPattern>>& target, Value, GlobalObject&, bool first_assignment = false, Environment* specific_scope = nullptr);
+    void assign(const FlyString& target, Value, GlobalObject&, bool first_assignment = false, Environment* specific_scope = nullptr);
+    void assign(const NonnullRefPtr<BindingPattern>& target, Value, GlobalObject&, bool first_assignment = false, Environment* specific_scope = nullptr);
 
-    Reference resolve_binding(GlobalObject&, FlyString const&, EnvironmentRecord* = nullptr);
+    Reference resolve_binding(GlobalObject&, FlyString const&, Environment* = nullptr);
 
     template<typename T, typename... Args>
     void throw_exception(GlobalObject& global_object, Args&&... args)
-- 
cgit v1.2.3