fix for getDefaultComputedStyles

pkg/web_components/lib/platform.concat.js

 /**
  * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
  * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
  * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
  * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
  * Code distributed by Google as part of the polymer project is also
  * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
  */
 
 window.Platform = window.Platform || {};
@@ skipping 7773 matching lines @@
           unwrapIfNeeded(el), pseudo);
     };
   }
 
   OriginalWindow.prototype.getSelection = function() {
     return wrap(this || window).getSelection();
   };
 
   // Work around for https://bugzilla.mozilla.org/show_bug.cgi?id=943065
   delete window.getComputedStyle;
+  delete window.getDefaultComputedStyle;
   delete window.getSelection;
 
   ['addEventListener', 'removeEventListener', 'dispatchEvent'].forEach(
       function(name) {
         OriginalWindow.prototype[name] = function() {
           var w = wrap(this || window);
           return w[name].apply(w, arguments);
         };
 
         // Work around for https://bugzilla.mozilla.org/show_bug.cgi?id=943065
@@ skipping 6785 matching lines @@
     return imported;
   }
 }
 
 // exports
 scope.flush = flush;
 
 })(window.Platform);
 
 
-//# sourceMappingURL=platform.concat.js.map
+//# sourceMappingURL=platform.concat.js.map