LibJS: Add support for async functions

This commit adds support for the most bare bones version of async
functions, support for async generator functions, async arrow functions
and await expressions are TODO.

1 files changed, 24 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/ExecutionContext.h b/Userland/Libraries/LibJS/Runtime/ExecutionContext.h
index 344205b917..5e0ce04953 100644
--- a/Userland/Libraries/LibJS/Runtime/ExecutionContext.h
+++ b/Userland/Libraries/LibJS/Runtime/ExecutionContext.h
@@ -22,6 +22,30 @@ struct ExecutionContext {
     {
     }
 
+    [[nodiscard]] ExecutionContext copy() const
+    {
+        ExecutionContext copy { arguments.copy() };
+
+        copy.function = function;
+        copy.realm = realm;
+        copy.lexical_environment = lexical_environment;
+        copy.variable_environment = variable_environment;
+        copy.private_environment = private_environment;
+        copy.current_node = current_node;
+        copy.function_name = function_name;
+        copy.this_value = this_value;
+        copy.is_strict_mode = is_strict_mode;
+
+        return copy;
+    }
+
+private:
+    explicit ExecutionContext(MarkedValueList existing_arguments)
+        : arguments(move(existing_arguments))
+    {
+    }
+
+public:
     FunctionObject* function { nullptr };                // [[Function]]
     Realm* realm { nullptr };                            // [[Realm]]
     Environment* lexical_environment { nullptr };        // [[LexicalEnvironment]]