Issue 2259 - Removed non-standard JavaScript code from Element Hiding Helper

lib/windowWrapper.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 let {Aardvark} = require("aardvark");
 let {Prefs} = require("prefs");
 let {KeySelector} = require("keySelector");
 
 let key = undefined;
 
 function getMenuItem()
 {
   // Randomize URI to work around bug 719376
   let stringBundle = Services.strings.createBundle("chrome://elemhidehelper/locale/global.properties?" + Math.random());
   let result = [stringBundle.GetStringFromName("selectelement.label"), stringBundle.GetStringFromName("stopselection.label")];
 
-  getMenuItem = function() result;
+  getMenuItem = () => result;
   return getMenuItem();
 }
 
 exports.WindowWrapper = WindowWrapper;
 function WindowWrapper(wnd)
 {
   this.window = wnd;
 
   this.popupShowingHandler = this.popupShowingHandler.bind(this);
   this.popupHiddenHandler = this.popupHiddenHandler.bind(this);
@@ skipping 31 matching lines @@
   {
     this.window.removeEventListener("popupshowing", this.popupShowingHandler, false);
     this.window.removeEventListener("popuphidden", this.popupHiddenHandler, false);
     this.window.removeEventListener("keypress", this.keyPressHandler, false);
     this.window.removeEventListener("blur", this.hideTooltips, true);
   },
 
   E: function(id)
   {
     let doc = this.window.document;
-    this.E = function(id) doc.getElementById(id);
+    this.E = id => doc.getElementById(id);
     return this.E(id);
   },
 
   popupShowingHandler: function(event)
   {
     let popup = event.originalTarget;
     if (!/^(abp-(?:toolbar|status|menuitem)-)popup$/.test(popup.id))
       return;
 
     this.popupHiddenHandler(event);
@@ skipping 56 matching lines @@
   },
 
   toggleSelection: function()
   {
     if ("@adblockplus.org/abp/public;1" in Cc && this.browser != Aardvark.browser)
       Aardvark.start(this);
     else
       Aardvark.quit();
   }
 };