Sync web-platform-tests PR 32787 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/32787
Details from upstream follow.

Xiaocheng Hu <xiaochengh@chromium.org> wrote:

Revert "[LayoutNG] Add PropagateChildBreakValues flag to the ConstraintSpace"

This reverts commit 9ef53870dd7989885aceb015576bb7e7eb086422.

Reason for revert: Tentatively reverted to see if it's the culprit
of https://bugs.chromium.org/p/chromium/issues/detail?id=1295835

Original change's description:

[LayoutNG] Add PropagateChildBreakValues flag to the ConstraintSpace

This CL adds a new flag to the ConstraintSpace to propagate child break
values (initial-break-before and previous-break-after).

The flag is currently set when setting up the constraint space for
fragmentation. However, it will also be used in future changes outside
of the normal fragmentation pass to determine the initial-break-before
and final-break-after for rows.

The code that performs child break value propagation in
MovePastBreakpoint() was moved to the builder, and it is run
whenever the new flag is set to true.

This fixed a bug where we failed to propagate up the break values of
a child if there was no BFC block-offset. The reason was that we
never called BreakBeforeChildIfNeeded() in that case. By moving the
propagation to the builder, instead, we can ensure the break values
are correctly propagated in this case, as well.

Bug: 829028,1293291
Change-Id: I2afd288cad99d11a1c414aca5844d7a77afef46f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3433832
Reviewed-by: Ian Kilpatrick \<ikilpatrick@chromium.org>
Reviewed-by: Morten Stenshorne \<mstensho@chromium.org>
Commit-Queue: Alison Maher \<almaher@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#969018}

Bug: 829028,1293291,1295835
Change-Id: I41b6c7980bad463f223d05765c24d17af675ac97
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3448207
Auto-Submit: Xiaocheng Hu \<xiaochengh@chromium.org>
Commit-Queue: Rubber Stamper \<rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper \<rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#969149}

https://hg.mozilla.org/mozilla-central/rev/862278106597