Issue 4580 - Replace ext.i18n with i18n

lib/filterValidation.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 58 matching lines @@
    *
    * @return {string}
    */
   toString()
   {
     let message;
     if (this.reason)
       message = Utils.getString(this.reason);
     else
     {
-      message = ext.i18n.getMessage(
+      message = chrome.i18n.getMessage(
         this.type.replace(/-/g, "_"),
         "selector" in this ? "'" + this.selector + "'" : null
       );
     }
 
     if (this.lineno)
     {
-      message = ext.i18n.getMessage(
+      message = chrome.i18n.getMessage(
         "line", this.lineno.toLocaleString()
       ) + ": " + message;
     }
     return message;
   }
 };
 
 function isValidCSSSelector(selector)
 {
   let style = document.createElement("style");
@@ skipping 86 matching lines @@
 
     if (error)
     {
       error.lineno = i + 1;
       errors.push(error);
     }
   }
 
   return {filters, errors};
 };