disassemble on unit test failure

Change-Id: I072f5d72f64eb683cc90c2890313ee289487cff3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/214403
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
2 files changed