Call JS functions via native context instead of js builtins object.

src/harmony-reflect.js

Index: src/harmony-reflect.js
diff --git a/src/harmony-reflect.js b/src/harmony-reflect.js
index 5ad63e1a5cebbd73ded1c50a6247a72e7006a99f..1e6a7d2b7a37bde8d094694b48abc72279fd14ad 100644
--- a/src/harmony-reflect.js
+++ b/src/harmony-reflect.js
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// TODO(yangguo): Remove this file. Do all of this in
+//                Genesis::InitializeGlobal_harmony_reflect
+
 (function(global, utils) {
 
 'use strict';