When text has been selected in a QTextEdit and the left or right arrow
key is pressed, the cursor moves one character beyond the start or end
of the selection, when it shouldn't move past the selection. Fixed by
moving the cursor to the right place when a selection is active.
Task-number: QTBUG-22853
Change-Id: I9ea1863436db98627a6fd041ce554cf10be26493
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
(cherry picked from commit 1b031759ddfdab9703dfecac13f1ed318da3dafe)