[webkit-changes] [WebKit/WebKit] cf327c: [scroll-anchoring] Exclude isolated subtrees

[Nikos Mouchtaris]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: cf327c0480206b1724eba8ddf418bafadf7aa5c6
      https://github.com/WebKit/WebKit/commit/cf327c0480206b1724eba8ddf418bafadf7aa5c6
  Author: Nikolaos Mouchtaris <nmouchtaris at apple.com>
  Date:   2023-11-15 (Wed, 15 Nov 2023)

  Changed paths:
    M Source/WebCore/page/scrolling/ScrollAnchoringController.cpp

  Log Message:
  -----------
  [scroll-anchoring] Exclude isolated subtrees
https://bugs.webkit.org/show_bug.cgi?id=262335
rdar://116205746

Reviewed by Simon Fraser.

We should exclude subtrees that are marked as contain: paint and are
offscreen, as any descendents would be clipped to the parent. This doesn't
quite fix contain-paint-offscreen-container.html but we do select the correct
anchor element after this change.

* Source/WebCore/page/scrolling/ScrollAnchoringController.cpp:
(WebCore::ScrollAnchoringController::examineCandidate):

Canonical link: https://commits.webkit.org/270794@main