LibJS: Replace Object's create_empty() with create() taking a prototype

This now matches the spec's OrdinaryObjectCreate() across the board:
instead of implicitly setting the created object's prototype to
%Object.prototype% and then in many cases setting it to a nullptr right
away, it now has an 'Object* prototype' parameter with _no default
value_. This makes the code easier to compare with the spec, very clear
in terms of what prototype is being used as well as avoiding unnecessary
shape transitions.

Also fixes a couple of cases were we weren't setting the correct
prototype.

There's no reason to assume that the object would not be empty (as in
having own properties), so let's follow our existing pattern of
Type::create(...) and simply call it 'create'.

14 files changed, 42 insertions, 35 deletions

diff --git a/Userland/Applications/Spreadsheet/JSIntegration.cpp b/Userland/Applications/Spreadsheet/JSIntegration.cpp
index 8c87c6ac25..e13cc28c2e 100644
--- a/Userland/Applications/Spreadsheet/JSIntegration.cpp
+++ b/Userland/Applications/Spreadsheet/JSIntegration.cpp
@@ -263,7 +263,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::parse_cell_name)
     if (!position.has_value())
         return JS::js_undefined();
 
-    auto object = JS::Object::create_empty(global_object);
+    auto object = JS::Object::create(global_object, global_object.object_prototype());
     object->put("column", JS::js_string(vm, sheet_object->m_sheet.column(position.value().column)));
     object->put("row", JS::Value((unsigned)position.value().row));
 
@@ -293,7 +293,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::current_cell_position)
 
     auto position = current_cell->position();
 
-    auto object = JS::Object::create_empty(global_object);
+    auto object = JS::Object::create(global_object, global_object.object_prototype());
     object->put("column", JS::js_string(vm, sheet_object->m_sheet.column(position.column)));
     object->put("row", JS::Value((unsigned)position.row));
 
@@ -377,7 +377,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::column_arithmetic)
 }
 
 WorkbookObject::WorkbookObject(Workbook& workbook)
-    : JS::Object(*JS::Object::create_empty(workbook.global_object()))
+    : JS::Object(*JS::Object::create(workbook.global_object(), workbook.global_object().object_prototype()))
     , m_workbook(workbook)
 {
 }
diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index 8a8908ed2c..51021ef784 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -773,7 +773,6 @@ Value ClassExpression::execute(Interpreter& interpreter, GlobalObject& global_ob
             return {};
         }
         class_constructor->set_constructor_kind(Function::ConstructorKind::Derived);
-        Object* prototype = Object::create_empty(global_object);
 
         Object* super_constructor_prototype = nullptr;
         if (!super_constructor.is_null()) {
@@ -787,7 +786,7 @@ Value ClassExpression::execute(Interpreter& interpreter, GlobalObject& global_ob
             if (super_constructor_prototype_value.is_object())
                 super_constructor_prototype = &super_constructor_prototype_value.as_object();
         }
-        prototype->set_prototype(super_constructor_prototype);
+        auto* prototype = Object::create(global_object, super_constructor_prototype);
 
         prototype->define_property(vm.names.constructor, class_constructor, 0);
         if (interpreter.exception())
@@ -1683,7 +1682,7 @@ Value ObjectExpression::execute(Interpreter& interpreter, GlobalObject& global_o
 {
     InterpreterNodeScope node_scope { interpreter, *this };
 
-    auto* object = Object::create_empty(global_object);
+    auto* object = Object::create(global_object, global_object.object_prototype());
     for (auto& property : m_properties) {
         auto key = property.key().execute(interpreter, global_object);
         if (interpreter.exception())
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.cpp b/Userland/Libraries/LibJS/Bytecode/Op.cpp
index 69744b6c22..d0959adc09 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Op.cpp
@@ -130,7 +130,7 @@ void NewString::execute_impl(Bytecode::Interpreter& interpreter) const
 
 void NewObject::execute_impl(Bytecode::Interpreter& interpreter) const
 {
-    interpreter.accumulator() = Object::create_empty(interpreter.global_object());
+    interpreter.accumulator() = Object::create(interpreter.global_object(), interpreter.global_object().object_prototype());
 }
 
 void ConcatString::execute_impl(Bytecode::Interpreter& interpreter) const
@@ -307,7 +307,7 @@ void PushLexicalEnvironment::execute_impl(Bytecode::Interpreter& interpreter) co
 void Yield::execute_impl(Bytecode::Interpreter& interpreter) const
 {
     auto yielded_value = interpreter.accumulator().value_or(js_undefined());
-    auto object = JS::Object::create_empty(interpreter.global_object());
+    auto object = JS::Object::create(interpreter.global_object(), nullptr);
     object->put("result", yielded_value);
     if (m_continuation_label.has_value())
         object->put("continuation", Value(static_cast<double>(reinterpret_cast<u64>(&m_continuation_label->block()))));
diff --git a/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp b/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
index d1ee2d1aa7..f0aff26ef4 100644
--- a/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
@@ -75,8 +75,7 @@ void ArrayPrototype::initialize(GlobalObject& global_object)
     define_property(vm.well_known_symbol_iterator(), get(vm.names.values), attr);
 
     // 23.1.3.34 Array.prototype [ @@unscopables ], https://tc39.es/ecma262/#sec-array.prototype-@@unscopables
-    Object* unscopable_list = create_empty(global_object);
-    unscopable_list->set_prototype(nullptr);
+    auto* unscopable_list = Object::create(global_object, nullptr);
     unscopable_list->put(vm.names.copyWithin, Value(true));
     unscopable_list->put(vm.names.entries, Value(true));
     unscopable_list->put(vm.names.fill, Value(true));
diff --git a/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp b/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp
index 8fb800bf39..559d55f6c3 100644
--- a/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp
@@ -86,7 +86,7 @@ Value GeneratorObject::next_impl(VM& vm, GlobalObject& global_object, Optional<V
     if (vm.exception())
         return {};
 
-    auto result = Object::create_empty(global_object);
+    auto result = Object::create(global_object, global_object.object_prototype());
     result->put("value", previous_generated_value);
 
     if (m_done) {
diff --git a/Userland/Libraries/LibJS/Runtime/IteratorOperations.cpp b/Userland/Libraries/LibJS/Runtime/IteratorOperations.cpp
index 7ca56509d1..79d76212c0 100644
--- a/Userland/Libraries/LibJS/Runtime/IteratorOperations.cpp
+++ b/Userland/Libraries/LibJS/Runtime/IteratorOperations.cpp
@@ -124,7 +124,7 @@ MarkedValueList iterable_to_list(GlobalObject& global_object, Value iterable, Va
 Value create_iterator_result_object(GlobalObject& global_object, Value value, bool done)
 {
     auto& vm = global_object.vm();
-    auto* object = Object::create_empty(global_object);
+    auto* object = Object::create(global_object, global_object.object_prototype());
     object->define_property(vm.names.value, value);
     object->define_property(vm.names.done, Value(done));
     return object;
diff --git a/Userland/Libraries/LibJS/Runtime/JSONObject.cpp b/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
index 4830176608..2405e3e46f 100644
--- a/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
@@ -106,7 +106,7 @@ String JSONObject::stringify_impl(GlobalObject& global_object, Value value, Valu
         state.gap = String::empty();
     }
 
-    auto* wrapper = Object::create_empty(global_object);
+    auto* wrapper = Object::create(global_object, global_object.object_prototype());
     wrapper->define_property(String::empty(), value);
     if (vm.exception())
         return {};
@@ -396,11 +396,12 @@ JS_DEFINE_NATIVE_FUNCTION(JSONObject::parse)
     }
     Value result = parse_json_value(global_object, json.value());
     if (reviver.is_function()) {
-        auto* holder_object = Object::create_empty(global_object);
-        holder_object->define_property(String::empty(), result);
+        auto* root = Object::create(global_object, global_object.object_prototype());
+        auto root_name = String::empty();
+        root->define_property(root_name, result);
         if (vm.exception())
             return {};
-        return internalize_json_property(global_object, holder_object, String::empty(), reviver.as_function());
+        return internalize_json_property(global_object, root, root_name, reviver.as_function());
     }
     return result;
 }
@@ -426,7 +427,7 @@ Value JSONObject::parse_json_value(GlobalObject& global_object, const JsonValue&
 
 Object* JSONObject::parse_json_object(GlobalObject& global_object, const JsonObject& json_object)
 {
-    auto* object = Object::create_empty(global_object);
+    auto* object = Object::create(global_object, global_object.object_prototype());
     json_object.for_each_member([&](auto& key, auto& value) {
         object->define_property(key, parse_json_value(global_object, value));
     });
@@ -443,6 +444,7 @@ Array* JSONObject::parse_json_array(GlobalObject& global_object, const JsonArray
     return array;
 }
 
+// 25.5.1.1 InternalizeJSONProperty ( holder, name, reviver ), https://tc39.es/ecma262/#sec-internalizejsonproperty
 Value JSONObject::internalize_json_property(GlobalObject& global_object, Object* holder, const PropertyName& name, Function& reviver)
 {
     auto& vm = global_object.vm();
diff --git a/Userland/Libraries/LibJS/Runtime/Object.cpp b/Userland/Libraries/LibJS/Runtime/Object.cpp
index d63224e665..fee600bcba 100644
--- a/Userland/Libraries/LibJS/Runtime/Object.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Object.cpp
@@ -65,9 +65,15 @@ PropertyDescriptor PropertyDescriptor::from_dictionary(VM& vm, const Object& obj
     return descriptor;
 }
 
-Object* Object::create_empty(GlobalObject& global_object)
+// 10.1.12 OrdinaryObjectCreate ( proto [ , additionalInternalSlotsList ] ), https://tc39.es/ecma262/#sec-ordinaryobjectcreate
+Object* Object::create(GlobalObject& global_object, Object* prototype)
 {
-    return global_object.heap().allocate<Object>(global_object, *global_object.new_object_shape());
+    if (!prototype)
+        return global_object.heap().allocate<Object>(global_object, *global_object.empty_object_shape());
+    else if (prototype == global_object.object_prototype())
+        return global_object.heap().allocate<Object>(global_object, *global_object.new_object_shape());
+    else
+        return global_object.heap().allocate<Object>(global_object, *prototype);
 }
 
 Object::Object(GlobalObjectTag)
@@ -425,12 +431,14 @@ Value Object::get_own_property_descriptor_object(const PropertyName& property_na
     VERIFY(property_name.is_valid());
 
     auto& vm = this->vm();
+    auto& global_object = this->global_object();
+
     auto descriptor_opt = get_own_property_descriptor(property_name);
     if (!descriptor_opt.has_value())
         return js_undefined();
     auto descriptor = descriptor_opt.value();
 
-    auto* descriptor_object = Object::create_empty(global_object());
+    auto* descriptor_object = Object::create(global_object, global_object.object_prototype());
     if (descriptor.is_data_descriptor()) {
         descriptor_object->define_property(vm.names.value, descriptor.value.value_or(js_undefined()));
         descriptor_object->define_property(vm.names.writable, Value(descriptor.attributes.is_writable()));
diff --git a/Userland/Libraries/LibJS/Runtime/Object.h b/Userland/Libraries/LibJS/Runtime/Object.h
index 444a67e84e..64df83284d 100644
--- a/Userland/Libraries/LibJS/Runtime/Object.h
+++ b/Userland/Libraries/LibJS/Runtime/Object.h
@@ -40,7 +40,7 @@ struct PropertyDescriptor {
 
 class Object : public Cell {
 public:
-    static Object* create_empty(GlobalObject&);
+    static Object* create(GlobalObject&, Object* prototype);
 
     explicit Object(Object& prototype);
     explicit Object(Shape&);
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp b/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
index 99245c513e..d59659fce0 100644
--- a/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
@@ -62,10 +62,13 @@ ObjectConstructor::~ObjectConstructor()
 // 20.1.1.1 Object ( [ value ] ), https://tc39.es/ecma262/#sec-object-value
 Value ObjectConstructor::call()
 {
-    auto value = vm().argument(0);
+    auto& vm = this->vm();
+    auto& global_object = this->global_object();
+
+    auto value = vm.argument(0);
     if (value.is_nullish())
-        return Object::create_empty(global_object());
-    return value.to_object(global_object());
+        return Object::create(global_object, global_object.object_prototype());
+    return value.to_object(global_object);
 }
 
 // 20.1.1.1 Object ( [ value ] ), https://tc39.es/ecma262/#sec-object-value
@@ -191,8 +194,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::from_entries)
     if (vm.exception())
         return {};
 
-    auto* object = Object::create_empty(global_object);
-    object->set_prototype(global_object.object_prototype());
+    auto* object = Object::create(global_object, global_object.object_prototype());
 
     get_iterator_values(global_object, iterable, [&](Value iterator_value) {
         if (vm.exception())
@@ -344,8 +346,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::create)
         return {};
     }
 
-    auto* object = Object::create_empty(global_object);
-    object->set_prototype(prototype);
+    auto* object = Object::create(global_object, prototype);
 
     if (!properties.is_undefined()) {
         object->define_properties(properties);
diff --git a/Userland/Libraries/LibJS/Runtime/ProxyConstructor.cpp b/Userland/Libraries/LibJS/Runtime/ProxyConstructor.cpp
index 2e14800e42..d948ed5bbf 100644
--- a/Userland/Libraries/LibJS/Runtime/ProxyConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ProxyConstructor.cpp
@@ -81,7 +81,7 @@ JS_DEFINE_NATIVE_FUNCTION(ProxyConstructor::revocable)
     });
     revoker->define_property(vm.names.length, Value(0));
 
-    auto* result = Object::create_empty(global_object);
+    auto* result = Object::create(global_object, global_object.object_prototype());
     result->define_property(vm.names.proxy, proxy);
     result->define_property(vm.names.revoke, revoker);
     return result;
diff --git a/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp b/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp
index 9cb84e2164..3bb2fab46c 100644
--- a/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp
@@ -191,7 +191,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::exec)
 
     Value groups = js_undefined();
     if (result.n_named_capture_groups > 0) {
-        auto groups_object = create_empty(global_object);
+        auto groups_object = Object::create(global_object, nullptr);
         for (auto& entry : result.named_capture_group_matches[0])
             groups_object->define_property(entry.key, js_string(vm, entry.value.view.to_string()));
         groups = move(groups_object);
diff --git a/Userland/Libraries/LibJS/Runtime/VM.cpp b/Userland/Libraries/LibJS/Runtime/VM.cpp
index 5e1500b04a..3c776eaf88 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.cpp
+++ b/Userland/Libraries/LibJS/Runtime/VM.cpp
@@ -286,8 +286,7 @@ void VM::assign(const NonnullRefPtr<BindingPattern>& target, Value value, Global
             VERIFY(!property.pattern);
             JS::Value value_to_assign;
             if (property.is_rest) {
-                auto* rest_object = Object::create_empty(global_object);
-                rest_object->set_prototype(nullptr);
+                auto* rest_object = Object::create(global_object, nullptr);
                 for (auto& property : object->shape().property_table()) {
                     if (!property.value.attributes.has_enumerable())
                         continue;
@@ -406,7 +405,7 @@ Value VM::construct(Function& function, Function& new_target, Optional<MarkedVal
 
     Object* new_object = nullptr;
     if (function.constructor_kind() == Function::ConstructorKind::Base) {
-        new_object = Object::create_empty(global_object);
+        new_object = Object::create(global_object, nullptr);
         if (environment)
             environment->bind_this_value(global_object, new_object);
         if (exception())
diff --git a/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp b/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp
index c071b9d705..027c138919 100644
--- a/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp
+++ b/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp
@@ -362,8 +362,7 @@ void WebAssemblyInstanceObject::initialize(JS::GlobalObject& global_object)
     Object::initialize(global_object);
 
     VERIFY(!m_exports_object);
-    m_exports_object = JS::Object::create_empty(global_object);
-    m_exports_object->set_prototype(nullptr);
+    m_exports_object = JS::Object::create(global_object, nullptr);
     auto& instance = this->instance();
     for (auto& export_ : instance.exports()) {
         export_.value().visit(