Ensure to reset state of selecting by word/char for new selections

Previously this value was only updated when interacting with the
selection handles, so if you started a selection, entered by-char mode,
and then started another selection you would still be in by-char mode.
This resulted in incorrect behavior.

This CL alters the logic to update the handle state whenever the cursor
is placed which will included the initial long press to select a word.

Bug: 21301589
Change-Id: I15dbe6f2b76c7edd8ea4b3ba53e7107c47bc48fa