Issue 427 - Remove non-standard function and getter syntax

lib/io.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
@@ skipping 20 matching lines @@
 
 let IO = exports.IO =
 {
   /**
    * Retrieves the platform-dependent line break string.
    */
   get lineBreak()
   {
     let lineBreak = (Services.appinfo.OS == "WINNT" ? "\r\n" : "\n");
     delete IO.lineBreak;
-    IO.__defineGetter__("lineBreak", function() { return lineBreak; });
+    IO.__defineGetter__("lineBreak", () => lineBreak);
     return IO.lineBreak;
   },
 
   /**
    * Tries to interpret a file path as an absolute path or a path relative to
    * user's profile. Returns a file or null on failure.
    */
   resolveFilePath: function(/**String*/ path) /**nsIFile*/
   {
     if (!path)
@@ skipping 283 matching lines @@
         else
           callback(e);
       });
     }
     catch(e)
     {
       callback(e);
     }
   }
 }