Simple rebaseline tool:  Add support for ANGLE, DirectWrite builders. Set svn mime type to image/png.
Simple rebaseline tool:  Add support for ANGLE, DirectWrite builders.
Set svn mime type to image/png.

Review URL: https://codereview.appspot.com/6820054

csulmone/skia,csulmone/skia,csulmone/skia,csulmone/skia