LibJS: Evaluate this in terms of ResolveThisBinding

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/6e1932e8b2e

Userland/Libraries/LibJS/AST.cpp

@@ -1347,7 +1347,7 @@ Value SpreadExpression::execute(Interpreter& interpreter, GlobalObject& global_o
 Value ThisExpression::execute(Interpreter& interpreter, GlobalObject& global_object) const
 {
     InterpreterNodeScope node_scope { interpreter, *this };
-    return get_this_environment(interpreter.vm()).get_this_binding(global_object);
+    return interpreter.vm().resolve_this_binding(global_object);
 }
 
 void ThisExpression::dump(int indent) const

Userland/Libraries/LibJS/Runtime/VM.cpp

@@ -490,6 +490,13 @@ void VM::throw_exception(Exception& exception)
     unwind(ScopeType::Try);
 }
 
+// 9.4.4 ResolveThisBinding ( ), https://tc39.es/ecma262/#sec-resolvethisbinding
+Value VM::resolve_this_binding(GlobalObject& global_object)
+{
+    auto& environment = get_this_environment(*this);
+    return environment.get_this_binding(global_object);
+}
+
 String VM::join_arguments(size_t start_index) const
 {
     StringBuilder joined_arguments;

Userland/Libraries/LibJS/Runtime/VM.h

@@ -162,6 +162,8 @@ public:
         return running_execution_context().this_value;
     }
 
+    Value resolve_this_binding(GlobalObject&);
+
     Value last_value() const { return m_last_value; }
     void set_last_value(Badge<Bytecode::Interpreter>, Value value) { m_last_value = value; }
     void set_last_value(Badge<Interpreter>, Value value) { m_last_value = value; }