Right now, on iOS at least, we set isPrimary=false for a pointer once it's no longer in contact with the digitizer. That is incorrect, it should remain true until all events are dispatched provided it was the primary pointer when pointerdown was dispatched. Additionally, a pointer should only be primary if it was primary when touches started.
Created attachment 370222 [details]
Committed r245505: <https://trac.webkit.org/changeset/245505>