Allow font scaling setting persist

This hopefully fixes issue 3530. Bugs intruduced by previous commits, i.e.:
- font not visible if user preference for scaling has not been set
- font not visible for dialog (Volume dialog, toasts etc.)
should be fixed now. I have tested that commit quite extensively yet please
check if it doesn't introduce any unnoticed bugs before merging.

Change-Id: I67c28acd9629129d3f3b76177a063327529725ac