Add strikeout font metrics.

This also updates create_test_font so that it can be built, compiles,
and uses SkFontStyle instead of SkTypeface::Style.

BUG=b/63669723

Change-Id: I6eb0f851853f4721cf8e5052255b5b6750c3257f
Reviewed-on: https://skia-review.googlesource.com/24740
Reviewed-by: Cary Clark <caryclark@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Ben Wagner <bungeman@google.com>
14 files changed