Some work on issue #2286804: sometimes text field doesn't accept input

This doesn't really fix the problem being brought up here, but fixes a
related issue I found while investigating it -- if you tap a text view
enough to cause it to try to scroll, this will cause the touch to become
a scroll instead of a click, even if there is nothing to scroll.  So
often quick taps to bring up the IME would be canceled because they
became a non-scroll.

Unfortuntately after syncing the latest build, I was having a lot of
trouble reproducing the original problem.  I think I need to punt it to
MR2 at this point.

Change-Id: If1f0bf33de1b4d71c9f677cdad07639b7a3fb772