Notification 'x' button in popup fix

notification.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 73 matching lines @@
     if (!link)
       return;
     event.preventDefault();
     event.stopPropagation();
     ext.windows.getLastFocused(function(win) { win.openTab(link.href); });
   });
 
   var notificationElement = document.getElementById("notification");
   notificationElement.className = notification.severity;
   notificationElement.style.display = "block";
+  
+  document.getElementById("close-notification").addEventListener("click", function()
+  {
+    notificationElement.style.display = "none";
+  });
 });