Created attachment 396698 [details] testcase Start a slow swipe over an overflow:scroll, and we'll always latch on the main frame by mistake. The first event we get has zero deltas, so ScrollingTreeScrollingNode::canScrollWithWheelEvent() returns false for non-root nodes, and true for root nodes. Then we latch on the root node for the rest of the gesture.
<rdar://problem/61903663>
Created attachment 396703 [details] Patch
Committed r260224: <https://trac.webkit.org/changeset/260224> All reviewed patches have been landed. Closing bug and clearing flags on attachment 396703 [details].