TenFourFox Feature Parity Release 10 final is now available (downloads, hashes, release notes). This version is live now. Other than outstanding security updates, in this version I also retracted the change (by flipping the pref) for unique data URL origins in issue 525 because of some reported add-on incompatibility. I'm looking at a way add-ons can get around this with their existing code for FPR11, but you're warned: many sites rely on this behaviour to reduce their cross-site scriping surface, and we will have to turn it back on sooner or later.

The changes for FPR11 (December) and FPR12 will be smaller in scope mostly because of the holidays and my parallel work on the POWER9 JIT for Firefox on the Talos II. For the next couple FPRs I'm planning to do more ES6 work (mostly Symbol and whatever else I can shoehorn in) and to enable unique data URI origins, and possibly get requestIdleCallback into a releaseable state. Despite the slower pace, however, we will still be tracking the Firefox release schedule as usual.

http://tenfourfox.blogspot.com/2018/10/tenfourfox-fpr10-available.html