Add no-op NULL picture to bench_record.
Defaults of out/Release/bench_record are still fine; NULL's not too far off
from stable at 900 loops. But for focus on NULL, I'd recommend
something like out/Release/bench_record --loops 100000 --skps.
Also: fail on failures, print 2 significant digits instead of fixed 4.2.
BUG=skia:1850
R=tomhudson@chromium.org
Author: mtklein@google.com
Review URL: https://codereview.chromium.org/
136873002
git-svn-id: http://skia.googlecode.com/svn/trunk@13054
2bbb7eff-a529-9590-31e7-
b0007b416f81