[runtime] [proxy] Fix Object.prototype.propertyIsEnumerable to support proxies

src/js/v8natives.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 // ----------------------------------------------------------------------------
 // Imports
@@ skipping 189 matching lines @@
 
 
 // ECMA-262 - 15.2.4.6
 function ObjectIsPrototypeOf(V) {
   if (!IS_SPEC_OBJECT(V)) return false;
   var O = TO_OBJECT(this);
   return %_HasInPrototypeChain(V, O);
 }
 
 
-// ECMA-262 - 15.2.4.6
+// ES6 19.1.3.4
 function ObjectPropertyIsEnumerable(V) {
   var P = TO_NAME(V);
-  if (%_IsJSProxy(this)) {
-    // TODO(rossberg): adjust once there is a story for symbols vs proxies.
-    if (IS_SYMBOL(V)) return false;
-
-    var desc = GetOwnPropertyJS(this, P);
-    return IS_UNDEFINED(desc) ? false : desc.isEnumerable();
-  }
   return %IsPropertyEnumerable(TO_OBJECT(this), P);
 }
 
 
 // Extensions for providing property getters and setters.
 function ObjectDefineGetter(name, fun) {
   var receiver = this;
   if (IS_NULL(receiver) || IS_UNDEFINED(receiver)) {
     receiver = %GlobalProxy(ObjectDefineGetter);
   }
@@ skipping 1532 matching lines @@
 
 %InstallToContext([
   "global_eval_fun", GlobalEval,
   "object_value_of", ObjectValueOf,
   "object_to_string", ObjectToString,
   "object_get_own_property_descriptor", ObjectGetOwnPropertyDescriptor,
   "to_complete_property_descriptor", ToCompletePropertyDescriptor,
 ]);
 
 })