Make the externally connectable browser test clobber all of the builtins,

chrome/renderer/resources/extensions/image_util.js

 // Copyright 2013 The Chromium 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 function takes an object |imageSpec| with the key |path| -
 // corresponding to the internet URL to be translated - and optionally
 // |width| and |height| which are the maximum dimensions to be used when
 // converting the image.
 function loadImageData(imageSpec, callbacks) {
   var path = imageSpec.path;
@@ skipping 42 matching lines @@
   }
   img.src = path;
 }
 
 function on_complete_index(index, err, loading, finished, callbacks) {
   return function(width, height, imageData) {
     delete loading[index];
     finished[index] = { width: width, height: height, data: imageData };
     if (err)
       callbacks.onerror(index);
-    if (Object.keys(loading).length == 0)
+    if ($Object.keys(loading).length == 0)
       callbacks.oncomplete(finished);
   }
 }
 
 function loadAllImages(imageSpecs, callbacks) {
   var loading = {}, finished = [],
       index, pathname;
 
   for (var index = 0; index < imageSpecs.length; index++) {
     loading[index] = imageSpecs[index];
     loadImageData(imageSpecs[index], {
       oncomplete: on_complete_index(index, false, loading, finished, callbacks),
       onerror: on_complete_index(index, true, loading, finished, callbacks)
     });
   }
 }
 
 exports.loadImageData = loadImageData;
 exports.loadAllImages = loadAllImages;