Fix skiaparser on mac

Previously the mac build didn't have a SkFontMgr::Factory. I'm not sure
why it wasn't required before.
It looks like this wasn't caught by tests because we didn't
use any text in them.

Test: Added a test to cover this
Bug: 181180671
Change-Id: I51de5bc6f1215705e26dedfe996f31f2e8590acb
13 files changed