Issue 4795 - Use modern JavaScript syntax

lib/popupBlocker.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 popupBlocker */
 
 "use strict";
 
-let {defaultMatcher} = require("matcher");
-let {BlockingFilter} = require("filterClasses");
-let {stringifyURL, isThirdParty, extractHostFromFrame} = require("url");
-let {checkWhitelisted} = require("whitelisting");
-let {logRequest} = require("devtools");
+const {defaultMatcher} = require("matcher");
+const {BlockingFilter} = require("filterClasses");
+const {stringifyURL, isThirdParty, extractHostFromFrame} = require("url");
+const {checkWhitelisted} = require("whitelisting");
+const {logRequest} = require("devtools");
 
 let loadingPopups = Object.create(null);
 
 function hasLoadingPopups()
 {
   return Object.keys(loadingPopups).length > 0;
 }
 
 function forgetPopup(tabId)
 {
@@ skipping 78 matching lines @@
   if (checkWhitelisted(popup.sourcePage, frame))
   {
     forgetPopup(tabId);
   }
   else
   {
     popup.sourceFrame = frame;
     checkPotentialPopup(tabId, popup);
   }
 });