DawnTestContext: print validation errors with SkDebugf.

This helps to diagnose errors in DM tests.

Change-Id: Ib585e6e78c1d0a03493befe970558e6f9c9731a1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/298136
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Stephen White <senorblanco@google.com>
1 file changed