Store less raw pointers in containers in Source/rendering/.
Pull request: https://github.com/WebKit/WebKit/pull/17764
Committed 268000@main (8650e88882f1): <https://commits.webkit.org/268000@main> Reviewed commits have been landed. Closing PR #17764 and removing active labels.
<rdar://problem/115506118>
Re-opened since this is blocked by bug 261657
Pull request: https://github.com/WebKit/WebKit/pull/17864
Pull request: https://github.com/WebKit/WebKit/pull/18096
Committed 268343@main (18bfbbcf4444): <https://commits.webkit.org/268343@main> Reviewed commits have been landed. Closing PR #18096 and removing active labels.
Windows port is crashing after this change. Bug 261998 – [Win] REGRESSION(268343@main): Crash under WebCore::PositionedDescendantsMap::removeContainingBlock