Fix SkSpan supspan() add test

Change-Id: Ida683aa054fef977b91b3232b063f74344ffc2c9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/289448
Auto-Submit: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Herb Derby <herb@google.com>
2 files changed