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

chrome/renderer/resources/extensions/context_menus_custom_bindings.js

 // Copyright (c) 2012 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.
 
 // Custom binding for the contextMenus API.
 
 var binding = require('binding').Binding.create('contextMenus');
 
 var contextMenuNatives = requireNative('context_menus');
 var sendRequest = require('sendRequest').sendRequest;
@@ skipping 21 matching lines @@
     if (contextMenus.listening) {
       return;
     }
     contextMenus.listening = true;
     contextMenus.event.addListener(function() {
       // An extension context menu item has been clicked on - fire the onclick
       // if there is one.
       var id = arguments[0].menuItemId;
       var onclick = contextMenus.handlersForId(id)[id];
       if (onclick) {
-        onclick.apply(null, arguments);
+        $Function.apply(onclick, null, arguments);
       }
     });
   };
 
   apiFunctions.setHandleRequest('create', function() {
     var args = arguments;
     var id = contextMenuNatives.GetNextContextMenuId();
     args[0].generatedId = id;
     var optArgs = {
       customCallback: this.customCallback,
@@ skipping 39 matching lines @@
                                  function(name, request, response) {
     if (chrome.runtime.lastError) {
       return;
     }
     contextMenus.generatedIdHandlers = {};
     contextMenus.stringIdHandlers = {};
   });
 });
 
 exports.binding = binding.generate();