Gardening: Mac 10.6 expectations following r182920

There appear to be release vs. debug differences preventing a simple
rebaseline (or I'm just confused). Many of the 10.6 Debug results look
correct now, but I defer to the experts.

BUG=418091
TBR=eae@chromium.org,eustas@chromium.org,wangxianzhu@chromium.org

Review URL: https://codereview.chromium.org/615223008

git-svn-id: svn://svn.chromium.org/blink/trunk@183093 bbb929c8-8fbe-4397-9dbb-9b2b20218538