Issue 6891 - Rename FilterNotifier to filterNotifier

lib/filterNotifier.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/>.
  */
 
 "use strict";
 
 /**
- * @fileOverview This component manages listeners and calls them to distributes
+ * @fileOverview This component manages listeners and calls them to distribute
  * messages about filter changes.
  */
 
 const {EventEmitter} = require("./events");
 
 /**
- * This class allows registering and triggering listeners for filter events.
- * @class
+ * This object allows registering and triggering listeners for filter events.
+ * @type {EventEmitter}
  */
-exports.FilterNotifier = Object.create(new EventEmitter());
+let filterNotifier = new EventEmitter();
+
+exports.filterNotifier = filterNotifier;