Issue 4878 - Start using ESLint for adblockpluscore

lib/coreUtils.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";
+
 function desc(properties)
 {
   let descriptor = {};
   let keys = Object.keys(properties);
 
   for (let key of keys)
     descriptor[key] = Object.getOwnPropertyDescriptor(properties, key);
 
   return descriptor;
 }
 exports.desc = desc;
 
 function extend(cls, properties)
 {
   return Object.create(cls.prototype, desc(properties));
 }
 exports.extend = extend;