tree d7df428c3d02d85ec092f22eaef231f61842fbc0
parent bf2d1646fecb50484bd3eac8814a3d05c2035569
author Ian Kilpatrick <ikilpatrick@chromium.org> 1573534512 -0800
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> 1573535412 -0500

[LayoutNG] Disable first-tier OOF-cache when borders/scrollbars are present.

The first-tier OOF-cache attempts to skip all the OOF sizing and positioning
work required, as the other cache simply compares the constraint spaces
which can be (relatively) expensive to determine.

This first-tier cache works by comparing the available-size given to the
OOF-positioned descendant. If equal we can skip the OOF-positioned sizing
and positioning steps.

This mostly worked, however had an issue where the containing-block may have
added/removed a borders/scrollbars, but the available-size given remained
the same.

This resulted in an incorrectly positioned OOF-positioned node.

This fix disallows the first-tier cache when borders/scrollbars are present.
This is sufficiently rare that this cache still has a relatively high
hit-rate and is still relative cheap to calculate.

Bug: 1013866
Change-Id: I71d41d2c4b47bcff6412f395db2deabf2f6f3a8f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1891768
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Aleks Totic <atotic@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714394}