Don't try to render color fonts using distance fields.

Adds detection of ARGB mask format, which is only used for color fonts.

BUG=skia:2173
R=bungeman@google.com, reed@google.com, bsalomon@google.com, robertphillips@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/224903012

git-svn-id: http://skia.googlecode.com/svn/trunk@14098 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed