Previously this code was given a rectangle that was already outset
3 sigma. Thus, the 12 sigma check was correct. However, it is now
given the original rect so the check should be against 6 sigma.
Bug: chromium:995308
Change-Id: Ibd234c6de7ee4e993b174608bbad11209755f8b9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/239439
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>