Sync web-platform-tests PR 22736 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/22736
Details from upstream follow.

Ian Kilpatrick <ikilpatrick@chromium.org> wrote:

[LayoutNG] Don't set the SetIsPushedByFloats() flag on lineboxes.

If we had an empty linebox with a float inside it (and the float was
shifted due to other floats) it was possible for that linebox to fail
the DCHECK in:
ng_block_layout_algorithm.cc:1584
DCHECK(!normal_child_had_clearance || !is_self_collapsing);

Both of these conditions were true.

This patch changes so that we don't set the IsPushedByFloats flag on
lineboxes.

This changes one fragmentation test, which appears(?) to be incorrect or
debate-able.

We now have the same rendering of the mutlicol test as EdgeHTML did
previously.

Bug: 1064987
Change-Id: Ie326437a637cc57d1b17f91ac5e49847fd13c983
Reviewed-on: https://chromium-review.googlesource.com/2137377
WPT-Export-Revision: 5826cbaea767a3beb0ba27809042ab4108075d50

CI Results

Ran 12 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

PASS: 1

Links

Gecko CI (Treeherder)
GitHub PR Head
GitHub PR Base

https://hg.mozilla.org/mozilla-central/rev/77591709fd8c