fine-tune tolerance for pinchy quads in stroker

BUG=
R=jvanverth@google.com

Review URL: https://codereview.chromium.org/22947005

git-svn-id: http://skia.googlecode.com/svn/trunk@10753 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed