Filter Preferences: Template conditions not evaluating to a boolean are interpreted as true

chrome/content/ui/filters.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
@@ skipping 118 matching lines @@
     let nodeIterator = document.createNodeIterator(result, NodeFilter.SHOW_ELEMENT, null, false);
     for (let node = nodeIterator.nextNode(); node; node = nodeIterator.nextNode())
     {
       if (node.localName == "if")
         conditionals.push(node);
       for (let i = 0; i < node.attributes.length; i++)
       {
         let attribute = node.attributes[i];
         let len = attribute.value.length;
         if (len >= 2 && attribute.value[0] == "{" && attribute.value[len - 1] == "}")
-          attribute.value = Cu.evalInSandbox(attribute.value.substr(1, len - 2), sandbox);
+        {
+          let value = Cu.evalInSandbox(attribute.value.substr(1, len - 2), sandbox);
+          if (attribute.name == "condition")
+            value = value ? "true" : "false";
+          attribute.value = value;
+        }
       }
     }
 
     // Process <if> tags - remove if condition is false, replace by their children
     // if it is true
     for each (let node in conditionals)
     {
       let fragment = document.createDocumentFragment();
       let condition = node.getAttribute("condition");
       if (condition == "false")
@@ skipping 62 matching lines @@
    * data object.
    */
   getNodeForData: function(/**Node*/ parent, /**String*/ property, /**Object*/ data) /**Node*/
   {
     for (let child = parent.firstChild; child; child = child.nextSibling)
       if ("_data" in child && property in child._data && child._data[property] == data)
         return child;
     return null;
   }
 };