Improve failure handling in directFilterMaskGPU

Bug: 1265434
Change-Id: I81af9fe52a981cfad3154de77aeee32b97b4d34c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469856
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed