Fix icon animation

iconAnimation.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
  * 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/>.
  */
 
 iconAnimation = {
   _icons: new TabMap(),
   _animatedTabs: new TabMap(),
-  step: 0,
+  _step: 0,
 
   update: function(severity)
   {
     if (severity == this._severity)
        return;
 
     if (!this._severity)
       this._start();
 
     this._severity = severity;
@@ skipping 93 matching lines @@
 
       if (this._step < 10)
         suffix += "-" + this._step;
 
       path = path.replace(/(?=\..+$)/, suffix);
     }
 
     tab.browserAction.setIcon(path);
   }
 };