Only scroll on screen when necessary.

Bug:3367446

bringPointIntoView was called by TextView in onPreDraw. This was
passing a message to the webcore thread to change the scroll
position.  This is unnecessary, because typically the scroll
position will be changed by webkit when keys are pressed. The
one situation where this helped was when the user taps on a
textfield, which brings up the IME, which may cover it. A better
solution is to tell webkit to scroll it on screen once the
screen size changes.  I have a CL in external/webkit to do that:
https://android-git.corp.google.com/g/#change,91095

Change-Id: I6e06ad59e1a1c99365bb5be635a43d1b88658c0d