Ensure that apps crash if they throw exceptions.

Previously, if an app threw an uncaught exception in an input,
vsync or native activity callback, it would log the exception then
continue limping merrily along.  In the case of input, it
could result in an ANR occurring because we had not drained
all of the pending input events and marked them as finished
(we only marked the most recent one finished).

Bug: 6304124
Change-Id: I87d76f7fd605e1a8af1237c66d8d62973080277e