[es6] Support optional "receiver" argument in Reflect.get.

src/builtins.cc

 // 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.
 
 #include "src/builtins.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
@@ skipping 1456 matching lines @@
       isolate, result, JSReceiver::DeletePropertyOrElement(
                            Handle<JSReceiver>::cast(target), name));
 
   return *result;
 }
 
 
 // ES6 section 26.1.6 Reflect.get
 BUILTIN(ReflectGet) {
   HandleScope scope(isolate);
-  DCHECK_LE(3, args.length());
-  DCHECK_LE(args.length(), 4);
-  Handle<Object> target = args.at<Object>(1);
-  Handle<Object> key = args.at<Object>(2);
-  // Handle<Object> receiver = args.length() == 4 ? args.at<Object>(3) : target;
-  //
-  // TODO(neis): We ignore the receiver argument for now because
-  // GetPropertyOrElement doesn't support it yet.
+  Handle<Object> undef = isolate->factory()->undefined_value();
+  Handle<Object> target = args.length() > 1 ? args.at<Object>(1) : undef;
+  Handle<Object> key = args.length() > 2 ? args.at<Object>(2) : undef;
+  Handle<Object> receiver = args.length() > 3 ? args.at<Object>(3) : target;
 
   if (!target->IsJSReceiver()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kCalledOnNonObject,
                               isolate->factory()->NewStringFromAsciiChecked(
                                   "Reflect.get")));
   }
 
   Handle<Name> name;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, name,
                                      Object::ToName(isolate, key));
 
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, result, Object::GetPropertyOrElement(target, name));
+      isolate, result, Object::GetPropertyOrElement(
+          Handle<JSReceiver>::cast(target), name, receiver));
 
   return *result;
 }
 
 
 // ES6 section 26.1.9 Reflect.has
 BUILTIN(ReflectHas) {
   HandleScope scope(isolate);
   DCHECK_EQ(3, args.length());
   Handle<Object> target = args.at<Object>(1);
@@ skipping 692 matching lines @@
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 }  // namespace internal
 }  // namespace v8