Set scissor to clip bounding box when using GrConvexPolyEffect

BUG=skia:2051
R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/156843005

git-svn-id: http://skia.googlecode.com/svn/trunk@13361 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed