Issue 4795 - Use modern JavaScript syntax

lib/icon.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 167 matching lines @@
 }
 
 let stopIconAnimation =
 /**
  * Stops to animate the browser action icon
  * after the current interval has been finished.
  *
  * @return {Promise} A promise that is fullfilled when
  *                   the icon animation has been stopped.
  */
-exports.stopIconAnimation = function()
+exports.stopIconAnimation = () =>
 {
   stopRequested = true;
   return notRunning.then(() =>
   {
     stopRequested = false;
   });
 };
 
 /**
  * Starts to animate the browser action icon to indicate a pending notifcation.
  * If the icon is already animated, it replaces the previous
  * animation as soon as the current interval has been finished.
  *
  * @param {string} type  The notification type (i.e: "information" or "critical")
  */
-exports.startIconAnimation = function(type)
+exports.startIconAnimation = type =>
 {
   notRunning = new Promise(resolve =>
   {
     Promise.all([renderFrames(type), stopIconAnimation()]).then(results =>
     {
       if (stopRequested)
       {
         resolve();
         return;
       }
 
       let frames = results[0];
       animateIcon(type, frames);
 
       let interval = setInterval(() =>
       {
         if (stopRequested)
         {
           clearInterval(interval);
           resolve();
           return;
         }
 
         animateIcon(type, frames);
       }, 10000);
     });
   });
 };