Issue 2260 - Replaced some more for..in loops with for..of fixing the UI

lib/appSupport.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 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 858 matching lines @@
       if (Policy.isWhitelisted(location.spec))
         UI.removeWhitelist(window);
       else
         UI.toggleFilter(Filter.fromText("@@||" + host + "^$document"));
     };
 
     let menuItem = null;
     onShutdown.add(function()
     {
       let window = null;
-      for (window in UI.applicationWindows)
+      for (window of UI.applicationWindows)
         break;
 
       if (window && menuItem)
         window.NativeWindow.menu.remove(menuItem);
     });
 
     UI.updateIconState = function fmn_updateIconState(window, icon)
     {
       if (menuItem !== null)
       {
@@ skipping 61 matching lines @@
             event.state = {id: require("info").addonID};
             browser._contentWindow.dispatchEvent(event);
           });
         });
       }, true);
     };
 
     break;
   }
 }