You will still be able to use HTTP with “localhost” addresses, but
only while your app is still in development mode.
You can change the App mode to Development Mode from App Dashboard:
In this mode you can only test your application with Facebook test user accounts. You can obtain the test accounts login credentials from your app dashboard.
Please note, http://localhost redirects are automatically allowed while in development mode only and do NOT need to be added in Valid OAuth Redirect URIs section.
Read more about it in this Facebook Blog.