Align GetIterator with ES6 spec

src/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.
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Object = global.Object;
 // var $Boolean = global.Boolean;
 // var $Number = global.Number;
 // var $Function = global.Function;
@@ skipping 1861 matching lines @@
     "toString", FunctionToString
   ));
 }
 
 SetUpFunction();
 
 
 // ----------------------------------------------------------------------------
 // Iterator related spec functions.
 
-// ES6 rev 26, 2014-07-18
-// 7.4.1 CheckIterable ( obj )
-function ToIterable(obj) {
-  if (!IS_SPEC_OBJECT(obj)) {
-    return UNDEFINED;
-  }
-  return obj[symbolIterator];
-}
-
-
-// ES6 rev 26, 2014-07-18
-// 7.4.2 GetIterator ( obj, method )
+// ES6 rev 33, 2015-02-12
+// 7.4.1 GetIterator ( obj, method )
 function GetIterator(obj, method) {
   if (IS_UNDEFINED(method)) {
-    method = ToIterable(obj);
+    method = ToObject(obj)[symbolIterator];
   }
   if (!IS_SPEC_FUNCTION(method)) {
     throw MakeTypeError('not_iterable', [obj]);
   }
   var iterator = %_CallFunction(obj, method);
   if (!IS_SPEC_OBJECT(iterator)) {
     throw MakeTypeError('not_an_iterator', [iterator]);
   }
   return iterator;
 }