Change flash.utils.getTimer()'s startup timestamp to when the first SWF's first frame is committed

This aligns much more closely with what the Flash Player does.
Delay AVM1 MovieClipLoader's INIT event by one frame

According to gospel, this is how it is done.
Add reftest for AVM1 MovieClipLoader
Merge pull request #1755 from tschneidereit/loader

More AVM1 MovieClipLoader fixes