Issue 3697 - Fall back to i18n.getUILanguage if @ui_locale isn't supported

safari/ext/common.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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 108 matching lines @@
     candidates.push(language);
 
     if (candidates.indexOf(defaultLocale) == -1)
       candidates.push(defaultLocale);
 
     return candidates;
   };
 
   var initCatalog = function(uiLocale)
   {
-    var bidiDir = /^(ar|fa|he|ug|ur)(_|$)/.test(uiLocale) ? "rtl" : "ltr";
     var catalog = Object.create(null);
-
     catalog["@@ui_locale"] = [uiLocale, []];
-    catalog["@@bidi_dir" ] = [bidiDir,  []];
 
     return catalog;
   };
 
   var locales = getLocaleCandidates();
   var catalog = initCatalog(locales[0]);
 
   var replacePlaceholder = function(text, placeholder, content)
   {
     return text.split("$" + placeholder + "$").join(content || "");
@@ skipping 70 matching lines @@
   };
 
 
   /* Utils */
 
   ext.getURL = function(path)
   {
     return safari.extension.baseURI + path;
   };
 })();