Align GetIterator with ES6 spec

test/mjsunit/es6/collections.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1174 matching lines @@
 })();
 
 
 function TestSetConstructorIterableValue(ctor) {
   'use strict';
   // Strict mode is required to prevent implicit wrapping in the getter.
   Object.defineProperty(Number.prototype, Symbol.iterator, {
     get: function() {
       assertEquals('object', typeof this);
       return function() {
+        assertEquals('number', typeof this);
         return oneAndTwo.keys();
       };
     },
     configurable: true
   });
 
   var set = new ctor(42);
   assertSize(2, set);
   assertTrue(set.has(k1));
   assertTrue(set.has(k2));
@@ skipping 170 matching lines @@
 })();
 
 
 function TestMapConstructorIterableValue(ctor) {
   'use strict';
   // Strict mode is required to prevent implicit wrapping in the getter.
   Object.defineProperty(Number.prototype, Symbol.iterator, {
     get: function() {
       assertEquals('object', typeof this);
       return function() {
+        assertEquals('number', typeof this);
         return oneAndTwo.entries();
       };
     },
     configurable: true
   });
 
   var map = new ctor(42);
   assertSize(2, map);
   assertEquals(1, map.get(k1));
   assertEquals(2, map.get(k2));
 
   delete Number.prototype[Symbol.iterator];
 }
 TestMapConstructorIterableValue(Map);
 TestMapConstructorIterableValue(WeakMap);
 
 function TestCollectionToString(C) {
   assertEquals("[object " + C.name + "]",
       Object.prototype.toString.call(new C()));
 }
 TestCollectionToString(Map);
 TestCollectionToString(Set);
 TestCollectionToString(WeakMap);
 TestCollectionToString(WeakSet);