Fix bug 3281956 - Cherry-picked from GB

DO NOT MERGE Fix bug 3124899 - timeout in CTS test
ExpandableListViewBasicTest

A certain sequence of events could cause AbsListView to enter an
infinite event loop. Only report reaching a scroll boundary to the
overscroll code path if the Scroller wants to move further, not if
we're done moving.

Change-Id: Ib61897f619e83b28f08b91e82f2b901cb1739e1a