Fix Gesture Select bug when user is in RTL mode.

For Gesture Select, we wanted to ensure if user ever moves beyond the
last item, we select everything up to the last item. This was assuming
the "blank area" is always to the right of the last item, which is not
true for RTL.

Bug: 31064020
Change-Id: I8d70b29c15b059b692c72a86fdb765305dd8dbfc