Augment gm shadows test to cover hairline paths

Note: this patch will cause gm/shadows to fail on all platforms until the test is re baselined.

REVIEW=http://codereview.appspot.com/5972065/



git-svn-id: http://skia.googlecode.com/svn/trunk@3612 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed