DSL was improperly allowing interface blocks in runtime shaders, which
caused PipelineStageGenerator to get upset.
Bug: oss-fuzz:38131
Change-Id: I593e68f2cab3db9151d606e65e2826ffa9c494e2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/446324
Commit-Queue: Ravi Mistry <rmistry@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
