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: Ifdaf72d60ca25584e4a37d3d8f17365e0fcbfa40