We were failing to handle the case where an animated scroll happens after a non-animated scroll.
<rdar://problem/117608836>
Pull request: https://github.com/WebKit/WebKit/pull/19663
Committed 269897@main (9b87cf844c2f): <https://commits.webkit.org/269897@main> Reviewed commits have been landed. Closing PR #19663 and removing active labels.