Increase test tolerance.

NOTREECHECKS=true

CQ_EXTRA_TRYBOTS=tryserver.skia:Test-Mac10.8-MacMini4.1-GeForce320M-x86_64-Release-Trybot

BUG=skia:
R=mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/516503003
1 file changed