Add workaround for Xoom crashing after discard removed from shader.

src/gpu/effects/GrConvexPolyEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrConvexPolyEffect.h"
 
 #include "gl/GrGLEffect.h"
@@ skipping 57 matching lines @@
                 builder->fsCodeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
                 builder->fsCodeAppend("\t\talpha *= edge;\n");
                 break;
             case GrConvexPolyEffect::kFillNoAA_EdgeType:
                 builder->fsCodeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
                 builder->fsCodeAppend("\t\talpha *= edge;\n");
                 break;
         }
     }
 
+    // Woe is me. See skbug.com/2149.
+    if (kTegra2_GrGLRenderer == builder->ctxInfo().renderer()) {
+        builder->fsCodeAppend("\t\tif (-1.0 == alpha) {\n\t\t\tdiscard;\n\t\t}\n");
+    }
     builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
                            (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
 }
 
 void GrGLConvexPolyEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
     size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
     if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
         uman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
         memcpy(fPrevEdges, cpe.getEdges(), byteSize);
@@ skipping 87 matching lines @@
                                             GrTexture*[]) {
     EdgeType edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCnt));
     int count = random->nextULessThan(kMaxEdges) + 1;
     SkScalar edges[kMaxEdges * 3];
     for (int i = 0; i < 3 * count; ++i) {
         edges[i] = random->nextSScalar1();
     }
 
     return GrConvexPolyEffect::Create(edgeType, count, edges);
 }