Sync web-platform-tests PR 32601 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/32601
Details from upstream follow.

Andreu Botella <abotella@igalia.com> wrote:

Fix performance bug with scrollable areas in subtree layout

This change fixes the perf test in
third_party/blink/perf_tests/layout/subtree-layout-scrollable-area.html
by limiting the number of scrollable areas that are added to the frame
view. This regressed in https://crrev.com/1931148, which added all areas
to the frame view.

The previous behavior of only adding scrollable areas which are visible
to hit-testing and not overflow: hidden no longer works, since such
areas must still be considered for scroll anchoring. However, scroll
anchoring does not apply to areas whose content is shorter (in the block
flow direction) than the scrollable area, and so scrollable areas which
don't overflow in the block flow direction do not need to be added to
the frame view.

(Do not merge before https://crrev.com/c/3423906, which adds the perf
test that this CL fixes.)

Bug: 1291551
Change-Id: I23270795b70d6a7d3b6f2c28cfc6e29d938f7943
Reviewed-on: https://chromium-review.googlesource.com/3424999
WPT-Export-Revision: 2b047d759dc6265054481ae9aca4e03166b50a06

CI Results

Ran 6 Firefox configurations based on mozilla-central, and Firefox, Chrome, and Safari on GitHub CI

Total 1 tests

Status Summary

Firefox

PASS: 1

Chrome

PASS: 1

Safari

FAIL: 1

Links

Gecko CI (Treeherder)
GitHub PR Head
GitHub PR Base

https://hg.mozilla.org/mozilla-central/rev/d05827984d24