Pointer Events interaction with drag and drop

Test Description: This test checks that the pointercancel (and if needed lostpointercapture) is dispatched when drag starts.
  1. Press down on the black square.
  2. Move your pointer to purple square and release.
  3. Repeat the first two steps.
  4. Repeat the first two steps once again.
Test passes if the proper behavior of the events is observed.