Issue 4796 - Use a modern JS engine in the browser tests and convert all files to ECMAScript 6

lib/common.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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/>.
  */
 
-// We are currently limited to ECMAScript 5 in this file, because it is being
-// used in the browser tests. See https://issues.adblockplus.org/ticket/4796
+"use strict";
 
 /**
  * Converts filter text into regular expression string
  * @param {string} text as in Filter()
  * @return {string} regular expression representation of filter text
  */
 function filterToRegExp(text)
 {
   return text
     // remove multiple wildcards
@@ skipping 14 matching lines @@
     // process anchor at expression end
     .replace(/\\\|$/, "$")
     // remove leading wildcards
     .replace(/^(\.\*)/, "")
     // remove trailing wildcards
     .replace(/(\.\*)$/, "");
 }
 
 if (typeof exports != "undefined")
   exports.filterToRegExp = filterToRegExp;