Fix a bug in ListView where touch scrolling could skip a data set change

Bug 2597058

ListView's touch scrolling can query the adapter for new views. As we now
flush pending touch events before running layout/draw traversals (when we
normally bring ListView back in sync), this can now happen more often.

Resync data before executing a scroll if a data set change is pending.

Change-Id: I3e4eba4c2537911ba9cb3393ee4d9e68e46f84bb