Use XMLHttpRequest constructor in JS modules

lib/objectTabs.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2013 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 137 matching lines @@
     }
 
     this.delayedShowParams = arguments;
 
     if (!this.initializing)
     {
       this.initializing = true;
 
       // Load CSS asynchronously
       try {
-        let request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Ci.nsIXMLHttpRequest);
+        let request = new XMLHttpRequest();
         request.mozBackgroundRequest = true;
         request.open("GET", "chrome://adblockplus/content/objtabs.css");
         request.overrideMimeType("text/plain");
 
         request.addEventListener("load", processCSSData.bind(this, request), false);
         request.send(null);
       }
       catch (e)
       {
         Cu.reportError(e);
@@ skipping 314 matching lines @@
     event.stopPropagation();
 
     objTabs.doBlock();
   }
   else if (event.type == "mouseover")
     objTabs.showTabFor(objTabs.currentElement);
   else if (event.type == "mouseout")
     objTabs.hideTabFor(objTabs.currentElement);
 }
 exports.objectMouseEventHander = objectMouseEventHander;