[Extensions] More bindings hardening

chrome/renderer/resources/extensions/automation/automation_node.js

 // Copyright 2014 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.
 
 var AutomationEvent = require('automationEvent').AutomationEvent;
 var automationInternal =
     require('binding').Binding.create('automationInternal').generate();
 var exceptionHandler = require('uncaught_exception_handler');
 var IsInteractPermitted =
     requireNative('automationInternal').IsInteractPermitted;
@@ skipping 972 matching lines @@
 }
 
 AutomationRootNode.getOrCreate = function(treeID) {
   return AutomationRootNodeImpl.getOrCreate(treeID);
 }
 
 AutomationRootNode.destroy = function(treeID) {
   AutomationRootNodeImpl.destroy(treeID);
 }
 
-exports.AutomationNode = AutomationNode;
-exports.AutomationRootNode = AutomationRootNode;
+exports.$set('AutomationNode', AutomationNode);
+exports.$set('AutomationRootNode', AutomationRootNode);