Issue 2709 - Removed legacy failsafe code form

lib/utils.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
  * 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/>.
  */
 
 var Utils = exports.Utils = {
   systemPrincipal: null,
   getString: function(id)
   {
-    if (typeof ext !== "undefined" && "i18n" in ext)
-      return ext.i18n.getMessage("global_" + id);
-    else
-      return id;
+    return ext.i18n.getMessage("global_" + id);
   },
   runAsync: function(callback)
   {
     if (document.readyState == "loading")
     {
       // Make sure to not run asynchronous actions before all
       // scripts loaded. This caused issues on Opera in the past.
       let onDOMContentLoaded = function()
       {
         document.removeEventListener("DOMContentLoaded", onDOMContentLoaded);
@@ skipping 73 matching lines @@
   {
     var Prefs = require("prefs").Prefs;
     var docLink = Prefs.documentation_link;
     return docLink.replace(/%LINK%/g, linkID).replace(/%LANG%/g, Utils.appLocale);
   },
 
   yield: function()
   {
   }
 };