The issue is being discussed on https://github.com/ubuntu/gnome-sdk/issues/49 now, one workaround is to do
$ mkdir ~/snap/firefox/current/.config/fontconfig/conf.d; cp /etc/fonts/conf.d/* ~/snap/firefox/current/.config/fontconfig/conf.d
The issue is being discussed on https:/ /github. com/ubuntu/ gnome-sdk/ issues/ 49 now, one workaround is to do
$ mkdir ~/snap/ firefox/ current/ .config/ fontconfig/ conf.d; cp /etc/fonts/conf.d/* ~/snap/ firefox/ current/ .config/ fontconfig/ conf.d