Issue 1840 - Fixed memory leak caused by "forward" messages

block.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 14 matching lines @@
 
   $("#addButton").click(addFilters);
   $("#cancelButton").click(closeDialog.bind(null, false));
 
   // Apply jQuery UI styles
   $("button").button();
 
   ext.backgroundPage.sendMessage(
   {
     type: "forward",
+    expectsResponse: true,
     payload:
     {
       type: "clickhide-init",
       width: Math.max(document.body.offsetWidth || document.body.scrollWidth),
       height: Math.max(document.body.offsetHeight || document.body.scrollHeight)
     }
   },
   function(response)
   {
     document.getElementById("filters").value = response.filters.join("\n");
@@ skipping 79 matching lines @@
     );
     dragCoords = [event.screenX, event.screenY];
   }
 }
 
 function onDragEnd(event)
 {
   onDrag(event);
   dragCoords = null;
 }