[Extensions] More bindings hardening

chrome/renderer/resources/extensions/input.ime_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 input ime API. Only injected into the
 // v8 contexts for extensions which have permission for the API.
 
 var binding = require('binding').Binding.create('input.ime');
 
 var Event = require('event_bindings').Event;
@@ skipping 39 matching lines @@
     var view;
     if (windowParams && windowParams.frameId) {
       view = appWindowNatives.GetFrame(
           windowParams.frameId, false /* notifyBrowser */);
       view.id = windowParams.frameId;
     }
     callback(view);
   });
 });
 
-exports.binding = binding.generate();
+exports.$set('binding', binding.generate());