Use the RunBuilders keyword to trigger required builds in rebaseline_webpage_images.py
Use the RunBuilders keyword to trigger required builds in rebaseline_webpage_images.py

Also adding base-macmini-10_8 to the list of supported gm_image_subdirs.

Created to fix http://code.google.com/p/skia/issues/detail?id=1126 : rebaseline_webpage_images.py should only trigger the affected buildbot builds.

Documentation for the RunBuilders keyword is here: https://sites.google.com/site/skiadocs/developer-documentation/the-skia-buildbots/power-tools-for-buildbot-maintainers

(SkipBuildbotRuns)
Review URL: https://codereview.appspot.com/7337049

git-svn-id: 32fc27f4dcfb6c0385cd9719852b95fe6680452d@7789 2bbb7eff-a529-9590-31e7-b0007b416f81

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