[builtins] implement Array.prototype[@@iterator] in TFJ builtins

src/js/prologue.js

 // Copyright 2015 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, utils, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 203 matching lines @@
     "species_symbol",
     "match_symbol",
     "replace_symbol",
     "search_symbol",
     "split_symbol",
   ];
 
   var filtered_exports = {};
   %OptimizeObjectForAddingMultipleProperties(
       filtered_exports, expose_list.length);
-  for (var key of expose_list) {
+  for (var i = 0; i < expose_list.length; ++i) {
+    var key = expose_list[i];
     filtered_exports[key] = exports_container[key];
   }
   %ToFastProperties(filtered_exports);
   exports_container = filtered_exports;
 
   utils.PostNatives = UNDEFINED;
   utils.ImportFromExperimental = UNDEFINED;
 }
 
 
@@ skipping 100 matching lines @@
 
 extrasUtils.uncurryThis = function uncurryThis(func) {
   return function(thisArg, ...args) {
     return %reflect_apply(func, thisArg, args);
   };
 };
 
 %ToFastProperties(extrasUtils);
 
 })