Added missing import for filterClasses.ActiveFilter to the background page

background.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/>.
  */
 
 with(require("filterClasses"))
 {
   this.Filter = Filter;
+  this.ActiveFilter = ActiveFilter;
   this.RegExpFilter = RegExpFilter;
   this.BlockingFilter = BlockingFilter;
   this.WhitelistFilter = WhitelistFilter;
 }
 with(require("subscriptionClasses"))
 {
   this.Subscription = Subscription;
   this.DownloadableSubscription = DownloadableSubscription;
 }
 with(require("whitelisting"))
@@ skipping 553 matching lines @@
   tab.sendMessage({type: "clickhide-deactivate"});
   refreshIconAndContextMenu(tab);
 });
 
 setTimeout(function()
 {
   var notificationToShow = Notification.getNextToShow();
   if (notificationToShow)
     showNotification(notificationToShow);
 }, 3 * 60 * 1000);