Add a gm for the labyrinth bug

Bug: chromium:913223
Change-Id: I1e229af7fbc61f316fccdc4c7ece27de5932be60
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/229479
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
2 files changed