Fixing overlap pane offset when shortcut card disappears.

When the shortcut card was hidden due to the call log being cleared, the
offset for the overlapping pane needed to be recalculated based on the
new height of the top portion of the dialtacts activity.

Bug: 18849546
Change-Id: Ib5953a2a537e9a7520d4f022e43fa974f67eb410