Issue 2067 - Unify logic retrieving the UI locale

i18n.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 // This variable should no longer be necessary once options.js in Chrome
 // accesses ext.i18n directly.
 var i18n = ext.i18n;
 
-if (ext.i18n.getMessage("@@ui_locale"))
-{
-  document.documentElement.lang = ext.i18n.getMessage("@@ui_locale").replace(/_/g, "-");
-  document.documentElement.dir = ext.i18n.getMessage("@@bidi_dir");
-}
-else
-{
-  // Getting UI locale cannot be done synchronously on Firefox, requires
-  // messaging the background page.
-  ext.backgroundPage.sendMessage({
+// Getting UI locale cannot be done synchronously on Firefox,
+// requires messaging the background page. For Chrome and Safari,
+// we could get the UI locale here, but would need to duplicate
+// the logic implemented in Utils.appLocale.
+ext.backgroundPage.sendMessage(
+  {
     type: "app.get",
     what: "localeInfo"
-  }, function(localeInfo)
+  },
+  function(localeInfo)
   {
     document.documentElement.lang = localeInfo.locale;
-    document.documentElement.dir = localeInfo.isRTL ? "rtl" : "ltr";
-  });
-}
+    document.documentElement.dir = localeInfo.bidiDir;
+  }
+);
 
 // Inserts i18n strings into matching elements. Any inner HTML already in the element is
 // parsed as JSON and used as parameters to substitute into placeholders in the i18n
 // message.
 ext.i18n.setElementText = function(element, stringName, arguments)
 {
   function processString(str, element)
   {
     var match = /^(.*?)<(a|strong)>(.*?)<\/\2>(.*)$/.exec(str);
     if (match)
@@ skipping 43 matching lines @@
 
   var now = new Date();
   if (d.toDateString() == now.toDateString())
     return [timeString];
   else
     return [timeString, d.toLocaleDateString()];
 }
 
 // Fill in the strings as soon as possible
 window.addEventListener("DOMContentLoaded", loadI18nStrings, true);