Fix bit-rot in the ATSUI code

But do we want to keep that code still around? I would love to drop
it. Using only CoreText would make some planned refactoring of OS X
and iOS code much simpler.

Change-Id: I9514c254791ea462d528e3e83b4927ac62a9f6ca
Surely ATSLayout is no friend of the CoreText AquaSalGraphics

Change-Id: I81725b388311ad9aade52906b4c5a6263b6bc104