Use GrConvexPolyEffect when clip is a single convex polygon

BUG=skia:2051

Committed: http://code.google.com/p/skia/source/detail?r=13286

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/151523005

git-svn-id: http://skia.googlecode.com/svn/trunk@13306 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/GLProgramsTest.cpp b/tests/GLProgramsTest.cpp
index 6c4aace..f320735 100644
--- a/tests/GLProgramsTest.cpp
+++ b/tests/GLProgramsTest.cpp
@@ -173,6 +173,7 @@
                                                                             this->getContext(),
                                                                             *this->caps(),
                                                                             dummyTextures));
+            SkASSERT(effect);
             int numAttribs = (*effect)->numVertexAttribs();
 
             // If adding this effect would exceed the max attrib count then generate a