Change SkFont to match needs of textblob

Tentative roadmap:
- land this
- extend TextBlobBuilder to take SkFont for its runs (eventually removing paint option)
- change SkTextBlob to store SkFont instead of SkRunFont (not critical, but makes sense)

After the above, (or during) also work towards:
- removing callers of SkPaint set... (textsize, textscalex, typeface, etc.)
- eventually physically remove those setters/getters/fields
- rev as desired the SkFont API to clean up flags, hinting, etc.

Bug: skia:2664
Change-Id: I0e323c58aef055e26d697911b078797453cb3626
Reviewed-on: https://skia-review.googlesource.com/c/163783
Commit-Queue: Mike Reed <reed@google.com>
Auto-Submit: Mike Reed <reed@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
4 files changed