Now that we implement didCompleteRenderingUpdateDisplay since 268770@main, we should notify the async scrolling tree.
Pull request: https://github.com/WebKit/WebKit/pull/18613
Committed 268843@main (e74fc9c77c97): <https://commits.webkit.org/268843@main> Reviewed commits have been landed. Closing PR #18613 and removing active labels.