PlatformEvent::GestureTap triggers a mousedown/mouseup/click event sequence.
Similarily, a double tap gesture should be sending mousedown/mouseup/click events with detail=2 (click count) and a dblclick event. Instead today it just behaves like two taps (eg. both with click count == 1).
Note that I can't implement this by consuming GestureDoubleTap. We want to send GestureTap for the second tap (eg. a element that listens just to taps should be triggerable over and over again), but the derived mouse events it generates need to be different (have a click count of 2).
Therefore I will add a tap count to GestureTap, analogous to the clickCount in PlatformMouseEvent
Whoops, I did already have a bug for this.
*** This bug has been marked as a duplicate of bug 92412 ***