If the user performed a very quick touch sequence without a response

from WebCore, then we would enter the ACTION_UP handler and cancel
pending touch events in WebCore's message queue. This cancellation
was orginally needed for Flash but the touch model for Flash has now changed
and it's no longer necessary. In the case of the layout test controller
the events do come very fast, and we were hitting this case so
WebCore was losing the events that got cancelled meaning that the
JS touch callbacks weren't getting invoked.

This was exposed by fast/events/basic-single-touch-events.html.

Change-Id: Icea09fb55a5b77f7ab9c19473cfa5ae272867a9a