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

src/objects.h

 // 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 1232 matching lines @@
       Isolate* isolate, Handle<Object> name, Handle<Object> value,
       LanguageMode language_mode);
   MUST_USE_RESULT static MaybeHandle<Object> SetDataProperty(
       LookupIterator* it, Handle<Object> value);
   MUST_USE_RESULT static MaybeHandle<Object> AddDataProperty(
       LookupIterator* it, Handle<Object> value, PropertyAttributes attributes,
       LanguageMode language_mode, StoreFromKeyed store_mode);
   MUST_USE_RESULT static inline MaybeHandle<Object> GetPropertyOrElement(
       Handle<Object> object, Handle<Name> name,
       LanguageMode language_mode = SLOPPY);
+  MUST_USE_RESULT static inline MaybeHandle<Object> GetPropertyOrElement(
+      Handle<JSReceiver> holder, Handle<Name> name, Handle<Object> receiver,
+      LanguageMode language_mode = SLOPPY);
   MUST_USE_RESULT static inline MaybeHandle<Object> GetProperty(
       Isolate* isolate, Handle<Object> object, const char* key,
       LanguageMode language_mode = SLOPPY);
   MUST_USE_RESULT static inline MaybeHandle<Object> GetProperty(
       Handle<Object> object, Handle<Name> name,
       LanguageMode language_mode = SLOPPY);
 
   MUST_USE_RESULT static MaybeHandle<Object> GetPropertyWithAccessor(
       LookupIterator* it, LanguageMode language_mode);
   MUST_USE_RESULT static MaybeHandle<Object> SetPropertyWithAccessor(
@@ skipping 9409 matching lines @@
   Handle<FixedArray> keys_;
   Handle<OrderedHashSet> set_;
   int length_;
   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
 };
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_