Update ObjectToString to Harmony-draft algorithm

src/arraybuffer.js

 // Copyright 2013 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.
 
 "use strict";
 
 var $ArrayBuffer = global.ArrayBuffer;
 
 // -------------------------------------------------------------------
 
@@ skipping 59 matching lines @@
   %CheckIsBootstrapping();
 
   // Set up the ArrayBuffer constructor function.
   %SetCode($ArrayBuffer, ArrayBufferConstructor);
   %FunctionSetPrototype($ArrayBuffer, new $Object());
 
   // Set up the constructor property on the ArrayBuffer prototype object.
   %AddNamedProperty(
       $ArrayBuffer.prototype, "constructor", $ArrayBuffer, DONT_ENUM);
 
+  %AddNamedProperty($ArrayBuffer.prototype,
+      symbolToStringTag, "ArrayBuffer", DONT_ENUM | READ_ONLY);
+
   InstallGetter($ArrayBuffer.prototype, "byteLength", ArrayBufferGetByteLen);
 
   InstallFunctions($ArrayBuffer, DONT_ENUM, $Array(
       "isView", ArrayBufferIsViewJS
   ));
 
   InstallFunctions($ArrayBuffer.prototype, DONT_ENUM, $Array(
       "slice", ArrayBufferSlice
   ));
 }
 
 SetUpArrayBuffer();