This reached Stage 3 at the November 2025 plenary, we can probably ship this in Firefox 148.

This update brings in tests for zip and zipKeyed. There's been a lot
of activity in Temporal tests over the past week, I've filed a bug to
track the new failures there.

Backed out for causing SM failures.

Backout link: https://hg-edge.mozilla.org/integration/autoland/rev/77c97dd853224cd95459ce7289741b937e74997b

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=815317c4986409a5ae730813f24c79eeb75c72bc&selectedTaskRun=bXlEg_HmRYm8C3KCQqkFtg.0

Failure logs:
https://treeherder.mozilla.org/logviewer?job_id=539551566&repo=autoland&task=bXlEg_HmRYm8C3KCQqkFtg.0&lineNumber=159653
https://treeherder.mozilla.org/logviewer?job_id=539557664&repo=autoland&task=HVmRsYIlRp2fQ9xd9G39LQ.0&lineNumber=55166

I've filed Bug 2005583 for the failing test, it passes locally. Hopefully that's the only problem: https://treeherder.mozilla.org/jobs?repo=try&selectedTaskRun=TNc4ARPTRSymPO9GHqwblw.0&revision=5aec35534a1fed5348075ed27a30cef12d546840.

https://hg.mozilla.org/mozilla-central/rev/1021aa79b6b7
https://hg.mozilla.org/mozilla-central/rev/98839e20c014

:dminor, could you consider nominating this for a release note? (Process info)

Release Note Request (optional, but appreciated)
[Why is this notable]: This adds two new methods for Iterators, Iterator.zip and Iterator.zipKeyed.
[Affects Firefox for Android]: Yes.
[Suggested wording]: The joint iteration proposal adds new Iterator.zip and Iterator.zipKeyed methods that allow zipping together underlying iterators into an iterator over values grouped by position, similar to zip in many other languages.
[Links (documentation, blog post, etc)]: https://github.com/tc39/proposal-joint-iteration

Thanks, added to the Fx148 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 Fx148 release notes.