Bug 195845 handles ScrollPositioningBehavior::Moving. See https://trac.webkit.org/changeset/243309/webkit for an example case where this is generated.
<rdar://problem/49117933>
Created attachment 365726 [details] patch
Note that one subtest fails because bug 196146 and the tests are also incorrectly clipped due to bug 196145
Comment on attachment 365726 [details] patch Clearing flags on attachment: 365726 Committed r243380: <https://trac.webkit.org/changeset/243380>
All reviewed patches have been landed. Closing bug.