Issue 6391 - Allow running the browser unit tests with Firefox

test/runners/firefox_download.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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/>.
  */
-
-/* eslint-env node */
-/* eslint no-console: "off" */
 
 "use strict";
 
 const {exec} = require("child_process");
 const fs = require("fs");
 const path = require("path");
 
 const {ncp} = require("ncp");
 
 const {download} = require("./download");
@@ skipping 144 matching lines @@
           return download(url, archive);
         }
         console.info(`Reusing cached archive ${archive}`);
       })
       .then(() => extractArchive(archive, browserDir))
       .then(() => browserDir);
   }).then(dir => getFirefoxExecutable(dir));
 }
 
 module.exports.ensureFirefox = ensureFirefox;