tree 2780de882c84c42196ec837b4e74551bdf078087
parent 496499a3188a8da571cbe59e182d555c2a6b8d69
author Ian Kilpatrick <ikilpatrick@chromium.org> 1582852882 -0800
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> 1582853995 -0800

Only allow positioned objects to be relayout boundaries.

Layout now generates some paint information on physical fragments.
Specifically (for this bug at least) if a sub-tree contains any floats.

This conflicted with the relayout boundary optimization. If a float was
added we wouldn't paint it, as we'd stop layout at the relayout
boundary, not telling the parent fragments that this subtree contained
a float.

This patch only allows relayout boundaries to occur at positioned
objects which always have self painting layers (which is the most
common self painting layer).

For the sites that I found which use this optimization (devtools,
facebook, bing) all occur on a positioned object.

Bug: 1049973
Change-Id: Iafaf68bf9642788a71e8f882a154e6acd7cbef46
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2076078
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745302}