Check Bug 1894779: Allow font-face urls to be resource:// urls and relax CORS for resource:// URLs

The font-face from resource:// will be interesting for Mullvad Browser and EOY.

However, we also have to check what is about CORS and resource:// now.

https://bugzilla.mozilla.org/show_bug.cgi?id=1894779

Thanks to @thorin for the head up.