The React-based rewrite looks whether there's a room name (in the
window's location) in order to choose between WelcomePage and
Conference. But app.js expects Conference to be rendered before it
builds a room name if WelcomePage is disabled and there's no room name.
A quick and dirty workaround is to render Conference within WelcomePage
so that the rendered result closely resembles index.html before the
React-based rewrite.

Don't use Array.prototype.sort() because (1) it operates in place and,
thus, mutes the Redux state and (2) it is not necessarily stable and,
thus, unnecessarily shuffles the thumbnails.