The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 'use strict';

 module.metadata = {

   "stability": "experimental"

 };

 // This is known as @@iterator in the ES6 spec.  Until it is bound to

 // some well-known name, find the @@iterator object by expecting it as

 // the first property accessed on a for-of iterable.

 const iteratorSymbol = (function() {

   try {

     for (var _ of Proxy.create({get: function(_, name) { throw name; } }))

       break;

   } catch (name) {

     return name;

   }

   throw new TypeError;

 })();

 exports.iteratorSymbol = iteratorSymbol;

 // An adaptor that, given an object that is iterable with for-of, is

 // suitable for being bound to __iterator__ in order to make the object

 // iterable in the same way via for-in.

 function forInIterator() {

     for (let item of this)

         yield item;

 }

 exports.forInIterator = forInIterator;