Fix intraline difference off-by-one when LF is added

If a region starts or ends with an LF we incorrectly shifted the
entire edit right by one character.  This meant the LF that was
modified didn't get colored, but the first common character after
the edit was colored incorrectly.  Only try to shift left if the
region doesn't start with LF.

Change-Id: I46bbfaf69c4e509328a10ab5a67fcc7cf6493abd
Signed-off-by: Shawn O. Pearce <sop@google.com>
1 file changed