Issue 4795 - Use modern JavaScript syntax

chrome/devtools.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/>.
  */
 
 "use strict";
 
 chrome.runtime.sendMessage(
   {
     type: "prefs.get",
     key: "show_devtools_panel"
   },
-  function(enabled)
+  enabled =>
   {
     if (enabled)
       chrome.devtools.panels.create("Adblock Plus",
                                     "icons/detailed/abp-48.png",
                                     "devtools-panel.html");
   }
 );