Issue 1663 - Emulate background page and implement proper message responder

ext/common.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 16 matching lines @@
   Page.prototype =
   {
     sendMessage: function(message)
     {
       this._source.postMessage({
         type: "message",
         messageId: -1,
         payload: message
       }, "*");
     }
-  }
+  };
+
+  global.ext.Page = Page;
 
   /* Message passing */
 
   global.ext.onMessage =
   {
     addListener: function(listener)
     {
       listener._extWrapper = function(event)
       {
         if (event.data.type != "message")
@@ skipping 138 matching lines @@
         }
 
         if (locales.length == 0)
           return "";
 
         readCatalog(locales.shift());
       }
     }
   };
 })(this);