Revert of Use GrConvexPolyEffect when clip is a single convex polygon (https://codere...

Revert of Use GrConvexPolyEffect when clip is a single convex polygon (https://codereview.chromium.org/151523005/)

Reason for revert:
unit tests crashing on windows?

Original issue's description:
> Use GrConvexPolyEffect when clip is a single convex polygon
>
> BUG=skia:2051
>
> Committed: http://code.google.com/p/skia/source/detail?r=13286

TBR=robertphillips@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2051

Review URL: https://codereview.chromium.org/142443006

git-svn-id: http://skia.googlecode.com/svn/trunk@13288 2bbb7eff-a529-9590-31e7-b0007b416f81