Replaced chrome.i18n by a platform-independent i18n object in UI

i18n.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
+var i18n = chrome.i18n;
+
 // Loads and 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.
 function loadI18nStrings()
 {
   var nodes = document.querySelectorAll("[class^='i18n_']");
   for(var i = 0; i < nodes.length; i++)
   {
     var arguments = JSON.parse("[" + nodes[i].textContent + "]");
     var className = nodes[i].className;
     if (className instanceof SVGAnimatedString)
       className = className.animVal;
     var stringName = className.split(/\s/)[0].substring(5);
     var prop = "innerHTML" in nodes[i] ? "innerHTML" : "textContent";
     if(arguments.length > 0)
-      nodes[i][prop] = chrome.i18n.getMessage(stringName, arguments);
+      nodes[i][prop] = i18n.getMessage(stringName, arguments);
     else
-      nodes[i][prop] = chrome.i18n.getMessage(stringName);
+      nodes[i][prop] = i18n.getMessage(stringName);
   }
 }
 
 // Provides a more readable string of the current date and time
 function i18n_timeDateStrings(when)
 {
   var d = new Date(when);
   var timeString = d.toLocaleTimeString();
 
   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);