Issue 5987 - Removes ext.windows

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
@@ skipping 558 matching lines @@
 
           return frames.get(0) || null;
         }
       };
     }
 
     return ext.onMessage._dispatch(
       message, sender, sendResponse
     ).includes(true);
   });
-
-
-  /* Windows */
-  ext.windows = {
-    create(createData, callback)
-    {
-      browser.windows.create(createData, createdWindow =>
-      {
-        afterTabLoaded(callback)(createdWindow.tabs[0]);
-      });
-    }
-  };
 }