Handle strikeout metrics in SkScalerContext_Mac

While the SkFontMetrics flags were being set correctly to indicate that
that the strikeout metrics were invalid, the strikeout metrics were also
not set, leading to indeterminate results from SkFontMetrics::operator==
Ensure that these metrics are set and also attempt to set them to the
correct values if possible.

Change-Id: I4a47b55f9bbde944bd33d9c6de1294b2c5a8f2de
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/633958
Reviewed-by: John Stiles <johnstiles@google.com>
Reviewed-by: Julia Lavrova <jlavrova@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
1 file changed