Fix TextView ActionMode overflow finishes the ActionMode

stopSelectionActionMode() was called within hideCursors, and this
gets called in many scenarios. One of them is onWindowFocusChanged,
which is triggered when the user clicks the overflow icon in the
action bar. Removed the action mode call from this use case.

Bug: 21267270
Change-Id: I1cd359e87de67141627e25d2ec520fc91303a48d