Double pageChangeComplete events

# Problem
scrollToItem outside of rendered range causes two pageChangeComplete dispatches one on page0, the other on the actual page you are going to.

# Solution
Set the prerender of the layout to the correct target position, so the double notification goes away.

CR: @timmccall-wf @lancefisher-wf @robbecker-wf @patkujawa-wf @georgelesica-wf @todbachman-wf 

Maybe I should have just done toHaveBeenCalled, so that this unit test isn't replicating arithmetic.