[webkit-changes] [WebKit/WebKit] b74266: Safari 18 regression: revert-layer is broken when ...

[Antti Koivisto]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: b7426636d8785247f4c1689f3295f8fb4ebacff1
      https://github.com/WebKit/WebKit/commit/b7426636d8785247f4c1689f3295f8fb4ebacff1
  Author: Antti Koivisto <antti at apple.com>
  Date:   2025-01-21 (Tue, 21 Jan 2025)

  Changed paths:
    A LayoutTests/fast/css/revert-layer-explicit-inherit-mdc-expected.html
    A LayoutTests/fast/css/revert-layer-explicit-inherit-mdc.html
    M Source/WebCore/style/PropertyCascade.cpp

  Log Message:
  -----------
  Safari 18 regression: revert-layer is broken when logical group CSS properties are explicitly inherited
https://bugs.webkit.org/show_bug.cgi?id=283942
rdar://140819138

Reviewed by Alan Baradlay.

This happens when we do partial applying of explicitly inherited properties after matched declarations
cache hit. If the property is a logical group property we also decide to apply all subsequent logical
group properties (as they might override this property). This is in itself fine.

However when applying revert-layer we need to construct a revert cascade that also includes lower priority layers.
We still limit the cascade building to explicitly inherited properties which may mean we miss a value from
a lower priority layer for a property we actually decided to apply.

* LayoutTests/fast/css/revert-layer-explicit-inherit-mdc-expected.html: Added.
* LayoutTests/fast/css/revert-layer-explicit-inherit-mdc.html: Added.
* Source/WebCore/style/PropertyCascade.cpp:
(WebCore::Style::PropertyCascade::PropertyCascade):

Fix by ensuring rollback cascade applies all properties.

Canonical link: https://commits.webkit.org/289183@main



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