seat: Do not assert on corner touch cases

Consider the cases where we get a touch move or touch up but we never
received a touch down before.

In the case of move, we'll simulate a touchDown right there and move on
with reality.
In the case of touch up, we'll just ignore the event as simulating could
just be more confusing.

BUG: 450338


(cherry picked from commit 073058c9)