Issue 1663 - Emulate background page and implement proper message responder

ext/content.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 (function(global)
 {
   if (!global.ext)
     global.ext = {};
 
   var backgroundFrame = document.createElement("iframe");
   backgroundFrame.setAttribute("src", "background.html" + window.location.search);
-  backgroundFrame.style.visibility = "hidden";
+  backgroundFrame.style.display = "none";
   window.addEventListener("DOMContentLoaded", function()
   {
     document.body.appendChild(backgroundFrame);
   }, false);
 
   var messageQueue = [];
   var maxMessageId = -1;
   var loadHandler = function(event)
   {
     if (event.data.type == "backgroundPageLoaded")
@@ skipping 28 matching lines @@
           if (event.data.type == "response" && event.data.messageId == rawMessage.messageId)
           {
             window.removeEventListener("message", callbackWrapper, false);
             responseCallback(event.data.payload);
           }
         };
         window.addEventListener("message", callbackWrapper, false);
       }
     }
   };
-
-  window.addEventListener("unload", function()
-  {
-    global.ext.backgroundPage.sendMessage({type: "removePage"});
-  }, false);
 })(this);