Add GetTypefaceOrDefault to SkPaintPriv

Remove most uses of GetDefaultTypeface. SkTypeface has
fewer friends.

BUG=skia:7515

Change-Id: Iedec5b39b9ef8c638772be4971075491b59b740b
Reviewed-on: https://skia-review.googlesource.com/112300
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
10 files changed