Replace SkTypeface::Style with SkFontStyle.

Review URL: https://codereview.chromium.org/488143002
Revert of Replace SkTypeface::Style with SkFontStyle. (patchset #9 id:160001 of https://codereview.chromium.org/488143002/)

Reason for revert:
CrOS GM failures:

[*] 2 ExpectationsMismatch: fontmgr_iter_565.png fontmgr_iter_8888.png

Original issue's description:
> Replace SkTypeface::Style with SkFontStyle.
>
> Committed: https://skia.googlesource.com/skia/+/43b8b36b20ae00e2d78421c4cda1f3f922983a20

TBR=reed@google.com,bungeman@google.com
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/667023002