Make sure to really save prefs when something changes

lib/prefs.js

 /*
  * This file is part of the Adblock Plus build tools,
  * 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 68 matching lines @@
   Prefs.__defineSetter__(name, function(newValue)
   {
     if (value == newValue)
       return value;
 
     try
     {
       ignorePrefChanges = true;
       writeFunc(branch, name, newValue);
       value = newValue;
+      Services.prefs.savePrefFile(null);
       triggerListeners(name);
     }
     catch(e)
     {
       Cu.reportError(e);
     }
     finally
     {
       ignorePrefChanges = false;
     }
@@ skipping 94 matching lines @@
 {
   let str = Cc["@mozilla.org/supports-string;1"].createInstance(Ci.nsISupportsString);
   str.data = newValue;
   branch.setComplexValue(pref, Ci.nsISupportsString, str);
 }
 
 function getJSONPref(branch, pref) JSON.parse(getCharPref(branch, pref))
 function setJSONPref(branch, pref, newValue) setCharPref(branch, pref, JSON.stringify(newValue))
 
 init();