Issue 3208 - Stop watching category removals

lib/contentPolicy.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 395 matching lines @@
     // be used in earlier releases.
     let httpTopic = "http-on-opening-request";
     if (Services.vc.compare(Utils.platformVersion, "18.0") < 0)
       httpTopic = "http-on-modify-request";
 
     Services.obs.addObserver(this, httpTopic, true);
     Services.obs.addObserver(this, "content-document-global-created", true);
 
     onShutdown.add(function()
     {
-      // Our category observers should be removed before changing category
-      // memberships, just in case.
       Services.obs.removeObserver(this, httpTopic);
       Services.obs.removeObserver(this, "content-document-global-created");
 
       for (let category of this.xpcom_categories)
         catMan.deleteCategoryEntry(category, this.contractID, false);
 
       // This needs to run asynchronously, see bug 753687
       Utils.runAsync(function()
       {
         registrar.unregisterFactory(this.classID, this);
@@ skipping 376 matching lines @@
   if (!wnd || wnd.closed)
     return;
 
   if (entry.type == Policy.type.OBJECT)
   {
     node.removeEventListener("mouseover", objectMouseEventHander, true);
     node.removeEventListener("mouseout", objectMouseEventHander, true);
   }
   Policy.processNode(wnd, node, entry.type, Utils.makeURI(entry.location), true);
 }