1557365 - [wpt-sync] Sync PR 16859 - [LayoutNG] Only reset a legacy cached result if OOF-positioned.

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect, P4)

Description

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 16859 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/16859
Details from upstream follow.

Ian Kilpatrick <[e-mail]> wrote:

[LayoutNG] Only reset a legacy cached result if OOF-positioned.

We had an issue with our simplified layout algorithm + relayout boundary
roots.

For this to trigger we needed a (legacy) layout object to be marked for
simplified layout which was also a relayout boundary root.

During LocalFrameView::PerformLayout, LayoutBox::UpdateLayout would run
on the legacy LayoutBox, and during LayoutBox::UpdateAfterLayout, this
would clear the LayoutBox::cached_layout_result_.

During another relayout boundary layout, we'd trigger simplified layout
for an NG node. This expects that there is always a cached layout
result associated with a box.
However this now wasn't the case, as the child had previously cleared
it, within LayoutBox::UpdateAfterLayout.

The guard inside LayoutBox::UpdateAfterLayout was designed to protect
against OOF-positioned nodes changing their layout parent, this
modifies that check do only clear the layout result of OOF-positioned
legacy layout objects.

Bug: 963387, 963433, 963620
Change-Id: Ice1202bdb939689e26e24a8690a52e7d7e82ecbc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1614082
Reviewed-by: Aleks Totic \<[e-mail]>
Commit-Queue: Ian Kilpatrick \<[e-mail]>
Cr-Commit-Position: refs/heads/master@{#660166}

Comment 1

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Pushed to try https://treeherder.mozilla.org/#/jobs?repo=try&revision=d14e2799c2d5e4cc91cd5dacebffcc4ffbbc431c

Comment 2

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=e82a11fb94b695038d0bb20761592754bf58fd9c

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/79f62b3613d8
[wpt PR 16859] - [LayoutNG] Only reset a legacy cached result if OOF-positioned., a=testonly

Comment 4

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/79f62b3613d8