Bug 899810 - Ensure that mFrameMetrics is updated properly in NotifyLayersUpdated. r=

In some cases the mScrollOffset was getting updated on the mFrameMetrics
before the IsDefault() check, so the IsDefault() check would return false
when it should have returned true. Calling IsDefault() on the
mFrameMetrics before writing stuff into it fixes this.
Bug 900742 - Fix APZC hit testing problem introduced by bug 866232. r=
Ensure that the APZCTreeManager gets input events in screen coordinates. r=
Logging
Apply proper transformations when sending inputs to the APZC and back to the DOM.
Squash to mapEventCoord