[es6] Iterators and generators should "extend" %IteratorPrototype%

src/string-iterator.js

 // 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.
 
 (function(global, shared, exports) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
-var GlobalObject = global.Object;
 var GlobalString = global.String;
 
 //-------------------------------------------------------------------
 
 var stringIteratorIteratedStringSymbol =
     GLOBAL_PRIVATE("StringIterator#iteratedString");
 var stringIteratorNextIndexSymbol = GLOBAL_PRIVATE("StringIterator#next");
 
 
 function StringIterator() {}
 
 
 // 21.1.5.1 CreateStringIterator Abstract Operation
 function CreateStringIterator(string) {
   var s = TO_STRING_INLINE(string);
   var iterator = new StringIterator;
   SET_PRIVATE(iterator, stringIteratorIteratedStringSymbol, s);
   SET_PRIVATE(iterator, stringIteratorNextIndexSymbol, 0);
   return iterator;
 }
 
 
-// 21.1.5.2.2 %StringIteratorPrototype%[@@iterator]
-function StringIteratorIterator() {
-  return this;
-}
-
-
 // 21.1.5.2.1 %StringIteratorPrototype%.next( )
 function StringIteratorNext() {
   var iterator = $toObject(this);
 
   if (!HAS_DEFINED_PRIVATE(iterator, stringIteratorNextIndexSymbol)) {
     throw MakeTypeError(kIncompatibleMethodReceiver,
                         'String Iterator.prototype.next');
   }
 
   var s = GET_PRIVATE(iterator, stringIteratorIteratedStringSymbol);
@@ skipping 28 matching lines @@
 }
 
 
 // 21.1.3.27 String.prototype [ @@iterator ]( )
 function StringPrototypeIterator() {
   return CreateStringIterator(this);
 }
 
 //-------------------------------------------------------------------
 
-%FunctionSetPrototype(StringIterator, new GlobalObject());
+%FunctionSetPrototype(StringIterator, {__proto__: $iteratorPrototype});
 %FunctionSetInstanceClassName(StringIterator, 'String Iterator');
 
 $installFunctions(StringIterator.prototype, DONT_ENUM, [
   'next', StringIteratorNext
 ]);
-$setFunctionName(StringIteratorIterator, symbolIterator);
-%AddNamedProperty(StringIterator.prototype, symbolIterator,
-                  StringIteratorIterator, DONT_ENUM);
 %AddNamedProperty(StringIterator.prototype, symbolToStringTag,
                   "String Iterator", READ_ONLY | DONT_ENUM);
 
 $setFunctionName(StringPrototypeIterator, symbolIterator);
 %AddNamedProperty(GlobalString.prototype, symbolIterator,
                   StringPrototypeIterator, DONT_ENUM);
 
 })