extend custom typeface gm

Change-Id: I472e009ed78e4652a56a3987af0c488a238908b0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290638
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed