Firefox is experimenting with a font whitelist as part of upstreaming of Tor features into Firefox trunk. These features are controlled by the privacy.resistFingerprinting pref. resistFingerprinting has some webcompat issues, but Mozilla is considering a subset of the protections for Privacy Browsing mode, similar to Tracking Protection. Here is the work-in-progress bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=1336208