quartz/display: add back scaling factor

With the last patches one thing that got lost if the scaling
factor. This is very visible when i.e loading a svg image
in a Retina display.
2 jobs for wip/nacho/quartz-scale-factor in 6 minutes and 14 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed build #171267

00:06:14

manual msys2-mingw32 #171268
win32 allowed to fail manual