Avoid potential IllegalArgumentException from trying to get the selection bounds
at the end of the text.  Often the selection start is equal to the character count
(meaning after the last character) and, though potentially a valid position, the
bounds is returned null and then we get an IllegalArgumentException from TextPaneSkin.
updateSelection.

This is potentially NOT the right solution to the problem, but doing it now to avoid
the exceptions until I can figure out a better solution (or what the REAL root
problem is).


git-svn-id: https://svn.apache.org/repos/asf/pivot/trunk@1566795 13f79535-47bb-0310-9956-ffa450edef68