Issue 4795 - Use modern JavaScript syntax

lib/notificationHelper.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 46 matching lines @@
       type: "question",
       title: ext.i18n.getMessage("overlay_notification_button_yes")
     });
     buttons.push({
       type: "question",
       title: ext.i18n.getMessage("overlay_notification_button_no")
     });
   }
   else
   {
-    const regex = /<a>(.*?)<\/a>/g;
+    let regex = /<a>(.*?)<\/a>/g;
     let match;
     while (match = regex.exec(message))
     {
       buttons.push({
         type: "link",
         title: match[1]
       });
     }
 
     // Chrome only allows two notification buttons so we need to fall back
@@ skipping 181 matching lines @@
   let methods = displayMethods[notificationType] || defaultDisplayMethods;
   return methods.indexOf(method) > -1;
 };
 
 ext.pages.onLoading.addListener(page =>
 {
   NotificationStorage.showNext(stringifyURL(page.url));
 });
 
 NotificationStorage.addShowListener(showNotification);