Sync web-platform-tests PR 34873 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/34873
Details from upstream follow.

Kent Tamura <tkent@chromium.org> wrote:

Revert "Fieldset NG: Fix paint order of OOF objects in a LEGEND and the"

This reverts commit 538bf46dd9ac492c74cf720bbde3d7fe2d681fe4.

Reason for revert: Performance regression. crbug.com/1345146

Original change's description:

Fieldset NG: Fix paint order of OOF objects in a LEGEND and the
corresponding anonymous content box.

If a FIELDSET is an OOF container, we made its anonymous content box
an OOF container by setting position:relative. It's bad because OOF
objects in the LEGEND is painted behind the anonymous content box. So
this CL updates OOF container conditions for anonymous fieldset content
boxes, and avoids setting position:relative.

• ng_fieldset_algorithm.cc:
  Handle NGBreakStatus::kDisableFragmentation.
  Without this change, floated-multicol-in-multicol-crash.html in WPT has
  a DCHECK failure.

Bug: 1341413
Change-Id: I650b3020df53eba5d05f930bc44675b80ff4e90b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3764404
Reviewed-by: Koji Ishii \<kojii@chromium.org>
Commit-Queue: Kent Tamura \<tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1025081}

Bug: 1341413, 1345146
Change-Id: Ibb66aaae44e15e7905ebd8c8210626f6d54ee45b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3767018
Bot-Commit: Rubber Stamper \<rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Kent Tamura \<tkent@chromium.org>
Commit-Queue: Rubber Stamper \<rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1025169}

https://hg.mozilla.org/mozilla-central/rev/275e89a606e5