Issue 4580 - Replace ext.devtools with devtools

ext/background.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";
 
 (function()
 {
   if (typeof ext == "undefined")
     window.ext = {};
 
   window.addEventListener("load", () =>
   {
-    parent.postMessage({
-      type: "backgroundPageLoaded"
-    }, "*");
-  }, false);
+    parent.postMessage({type: "backgroundPageLoaded"}, "*");
+  });
 
   function PageMap()
   {
     this._keys = [];
     this._values = [];
   }
   PageMap.prototype = {
     keys()
     {
       return this._keys.map((source) =>
@@ skipping 30 matching lines @@
       if (index >= 0)
       {
         this._keys.splice(index, 1);
         this._values.splice(index, 1);
       }
     }
   };
 
   window.ext.PageMap = PageMap;
 }());