Allow GrShadowRRectOp::Make to fail

Change-Id: Ia325c711143c76db27b7dd9dd02ea8bea13f2806
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209100
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
2 files changed