Add null proxy test to SkGpuDevice::drawProducerLattice

Bug: b/77917978

TBR=brianosman@google.com

Change-Id: Ib7ecb00dd0beac2444ca95106c2560c2b2940465
Reviewed-on: https://skia-review.googlesource.com/126509
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
1 file changed