Issue 4795 - Use modern JavaScript syntax

lib/tldjs.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/>.
  */
 
 /** @module tldjs */
 
+"use strict";
+
 let getDomain =
 /**
  * Get the base domain for given hostname.
  *
  * @param {string} hostname
  * @return {string}
  */
-exports.getDomain = function(hostname)
+exports.getDomain = hostname =>
 {
   let bits = hostname.split(".");
   let cutoff = bits.length - 2;
 
   for (let i = 0; i < bits.length; i++)
   {
     let offset = publicSuffixes[bits.slice(i).join(".")];
 
     if (typeof offset != "undefined")
     {
       cutoff = i - offset;
       break;
     }
   }
 
   if (cutoff <= 0)
     return hostname;
 
   return bits.slice(cutoff).join(".");
 }