commit 6027ff108f237aab0b2c8094883217b22a79c6bd
author Philip Rogers <pdr@chromium.org> Tue Jun 09 17:36:05 2020
committer Commit Bot <commit-bot@chromium.org> Tue Jun 09 17:36:05 2020
tree dd3c588c6be3a3a4c5429681481786382b38fb91
parent 95ae7845e500595071ffbd5a32f1584fef374066

Unify CSS grouping properties

This patch unifies the grouping property logic used for stacking
contexts (ComputedStyle::UpdateIsStackingContextWithoutContainment),
PaintLayer creation (LayoutBox::LayerTypeRequired), 3d transform
flattening (ComputedStyle::UsedTransformStyle3D), and svg isolation
(SVGLayoutSupport::IsIsolationRequired). Grouping properties
are specified in [1]. This patch reduces complexity and is likely to
improve performance with fewer checks in LayoutBox::LayerTypeRequired.

Box reflection (-webkit-box-reflect) only applies to boxes but is used
to create a stacking context for all objects. To avoid changing this
behavior, a parameter is used for HasGroupingProperty.

By recognizing CSS clip as a grouping property, compositing reason
finder is able to force layers for clips with composited descendants
(CSS clip -> HasClipRelatedProperty -> kClipsCompositingDescendants),
which results in some test changes.

[1] https://drafts.csswg.org/css-transforms-2/#grouping-property-values

Bug: 1068596
Change-Id: I86ca4a41b0324f2966c557dce6396b3bba684598
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2234541
Commit-Queue: Philip Rogers <pdr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776581}