add tests for SkDocument

R=reed@google.com, vandebo@chromium.org

Author: edisonn@google.com

Review URL: https://codereview.chromium.org/33423002

git-svn-id: http://skia.googlecode.com/svn/trunk@11907 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed