[Tracking Requested - why for this release]:

Central as Beta simulation:
https://treeherder.mozilla.org/#/jobs?repo=try&resultStatus=testfailed%2Cbusted%2Cexception%2Crunnable&classifiedState=unclassified&revision=593aa37ef063396bb253d23b17c3be9bc463bc28&selectedJob=232674985

Failure log:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=232674985&repo=try&lineNumber=1936

:botond , this seems to have been caused by https://hg.mozilla.org/integration/autoland/rev/c3c039fd4476. Could you please take a look?

What's happening here is that containerless scrolling landed on the Nightly channel only for now, and there were some accompanying test and test annotation changes.

I don't know of way to mark test or test annotation changes as Nightly-only.

This can be resolved in one of two ways:

1. We let containerless scrolling ride the 67 train to Beta. In this case, the failures will go away.
2. If we decide not to let containerless scrolling ride the 67 train, we can back out the test changes from 67 after it branches.

I will take this bug and use it to track the change in (2) if it becomes necessary.

The reftest sandbox has "release_or_beta": https://searchfox.org/mozilla-central/rev/d6f8590a91b71d64a1d0471cac38b6aadbe2a6e2/layout/tools/reftest/manifest.jsm#496

After discussing this with RyanVM, we settled on a solution that doesn't require waiting until the "ride the 67 train" decision is made: force the pref on for the affected tests.

They were revised in bug 1158392 to work with containerless scrolling and
not with container scrolling.

https://hg.mozilla.org/mozilla-central/rev/25bc4683d006

Verified fixed with latest beta simulation: https://treeherder.mozilla.org/#/jobs?repo=try&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel%2Crunnable&revision=23016e54866d3a6d3e2946688b33ca5ccb4dbfbd