[webkit-changes] [WebKit/WebKit] 01864f: ::backdrop is tree-abiding and should be allowed a...

[Ahmad Saleem]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 01864fd8625f9227ea7d965539fea4a7a47317a2
      https://github.com/WebKit/WebKit/commit/01864fd8625f9227ea7d965539fea4a7a47317a2
  Author: Ahmad Saleem <ahmad.saleem792+github at gmail.com>
  Date:   2023-11-30 (Thu, 30 Nov 2023)

  Changed paths:
    A LayoutTests/imported/w3c/web-platform-tests/css/css-position/backdrop-tree-abiding-slotted-expected.txt
    A LayoutTests/imported/w3c/web-platform-tests/css/css-position/backdrop-tree-abiding-slotted.html
    M LayoutTests/imported/w3c/web-platform-tests/css/css-position/w3c-import.log
    M Source/WebCore/css/parser/CSSSelectorParser.cpp

  Log Message:
  -----------
  ::backdrop is tree-abiding and should be allowed after ::slotted()

https://bugs.webkit.org/show_bug.cgi?id=265611

Reviewed by Tim Nguyen.

This patch is to align WebKIt with Blink / Chromium and Web-Specification [1]:

Merge: https://chromium-review.googlesource.com/c/chromium/src/+/4778566

[1] https://drafts.csswg.org/css-position-4/#backdrop

When ::backdrop was moved into css-position, it was made tree-abiding, which means
that '::slotted()::backdrop' should be allowed.

This PR also syncs WPT test from upstream:

Upstream Hash: https://github.com/web-platform-tests/wpt/commit/3e2d8fc027ffccb98d701560e7ed9d72343b549a

* Source/WebCore/css/parser/CSSSelectorParser.cpp:
(isTreeAbidingPseudoElement):
* LayoutTests/imported/w3c/web-platform-tests/css/css-position/w3c-import.log:
* LayoutTests/imported/w3c/web-platform-tests/css/css-position/backdrop-tree-abiding-slotted.html: Add Test Case
* LayoutTests/imported/w3c/web-platform-tests/css/css-position/backdrop-tree-abiding-slotted-expected.txt: Add Test Case Expectation

Canonical link: https://commits.webkit.org/271366@main