buildbots: Make CompareGMs examine GenerateGM's JSON summary to determine failure BUG=https://code.google.com/p/skia/issues/detail?id=1300 R=borenet@google.com
buildbots: Make CompareGMs examine GenerateGM's JSON summary to determine failure
BUG=https://code.google.com/p/skia/issues/detail?id=1300
R=borenet@google.com

Review URL: https://codereview.chromium.org/15520004

git-svn-id: 32fc27f4dcfb6c0385cd9719852b95fe6680452d@9240 2bbb7eff-a529-9590-31e7-b0007b416f81

google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot