Add GPU support for color bitmap fonts

BUG=skia:1869
R=bungeman@google.com, robertphillips@google.com, bsalomon@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/99993002

git-svn-id: http://skia.googlecode.com/svn/trunk@12471 2bbb7eff-a529-9590-31e7-b0007b416f81
6 files changed