This is for interop-2023 on the release channel. It looks like other browsers have shipped this feature, per wpt.fyi on stable.

Also, I expect https://github.com/w3c/csswg-drafts/issues/9640 doesn't block this shipment. Just need to be clear about what is the expected behavior for this cyclical dependency.

https://hg.mozilla.org/mozilla-central/rev/3152110c63b5

:emilio, sorry for the ping Boris has a PTO until Jan 15 status.
Could you consider nominating this for a release note?

Release Note Request (optional, but appreciated)
[Why is this notable]: Extension to the transform-box feature
[Affects Firefox for Android]: yes
[Suggested wording]: Support for the content-box and stroke-box of the transform-box CSS property.
[Links (documentation, blog post, etc)]: https://groups.google.com/a/mozilla.org/g/dev-platform/c/vAT8QMrodq8?pli=1 or this bug, probably?

Thanks, added to the Fx122 nightly release notes, please allow 30 minutes for the site to update.
Keeping the relnote-firefox flag as ? to keep it on the radar for inclusion in the final Fx122 release notes

Added needinfo on dholbert as a reminder to discuss backing this out for the moment.

Yeah, backing out (i.e. leaving this preffed on for Nightly but not release) makes sense to me, I think, until we can come up with a solution for bug 1870200. Though I'm curious for emilio's thoughts too.

Given we're in soft freeze now, and and there aren't signals that users are tripping over bug 1870200 right now (i.e. this isn't going to cause immediate trouble on Beta), I think we can take a look at backing out (or landing + uplifting a fix if we can think of one) next week after emilio's gotten a chance to weigh in.

Chatted with Emilio on slack, and he agrees we should hold off on letting this ride the trains for now. I'll ask for the pref-unguarding patch here to be backed out.

Donal, would you mind undoing the release-note inclusion in comment 8?

(I think that was just adding it to Nightly release notes -- it actually doesn't make too much sense for Nightly release notes anyway, since this has been supported on Nightly since August via https://hg.mozilla.org/mozilla-central/rev/473ebe5ec7aa4f1c5da45ed580fb56258737a210#l9.15 . The only change in this bug here was that we were removing the "Nightly-only" restriction. But we're now reimposing that restriction via backout, until we've addressed bug 1870200.)

Backed out as requested because it is not yet ready for shipping to release.

• Backout link

Release note from comment 8 removed

There is an r+ patch which didn't land and no activity in this bug for 2 weeks.
:boris, could you have a look please?
If you still have some work to do, you can add an action "Plan Changes" in Phabricator.
For more information, please visit BugBot documentation.

https://hg.mozilla.org/mozilla-central/rev/106f0088b3ce

Added to the Fx125 relnotes.

FF Release note PR