[es6] Partially implement Reflect.preventExtensions.

src/runtime/runtime-object.cc

 // Copyright 2014 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.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 286 matching lines @@
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                      GetOwnProperty(isolate, obj, name));
   return *result;
 }
 
 
 RUNTIME_FUNCTION(Runtime_PreventExtensions) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
-  CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
-  Handle<Object> result;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
-                                     JSObject::PreventExtensions(obj));
-  return *result;
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, obj, 0);
+  if (JSReceiver::PreventExtensions(obj, THROW_ON_ERROR).IsNothing())
+    return isolate->heap()->exception();
+  return *obj;
 }
 
 
 RUNTIME_FUNCTION(Runtime_IsExtensible) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
   return isolate->heap()->ToBoolean(JSObject::IsExtensible(obj));
 }
 
@@ skipping 1292 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_ObjectDefineProperties) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(Object, o, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, properties, 1);
   return JSReceiver::DefineProperties(isolate, o, properties);
 }
 }  // namespace internal
 }  // namespace v8