LibJS: Implement most of the Reflect object

Author: https://github.com/linusg
Commit: 79b829637e
Pull-request: https://github.com/SerenityOS/serenity/pull/2047
Reviewed-by: https://github.com/awesomekling

Libraries/LibJS/Interpreter.h

@@ -104,6 +104,7 @@ public:
     void exit_scope(const ScopeNode&);
 
     Value call(Function&, Value this_value = {}, Optional<MarkedValueList> arguments = {});
+    Value construct(Function&, Function& new_target, Optional<MarkedValueList> arguments = {});
 
     CallFrame& push_call_frame()
     {