Fix a crash on stroking empty paths with nv_path_rendering enabled

src/gpu/GrClipMaskManager.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrClipMaskManager.h"
 #include "GrAAConvexPathRenderer.h"
@@ skipping 673 matching lines @@
                                              kAlways_StencilFunc,
                                              0xffff,
                                              0x0000,
                                              0xffff);
                 SET_RANDOM_COLOR
                 if (Element::kRect_Type == element->getType()) {
                     *drawState->stencil() = gDrawToStencil;
                     fGpu->drawSimpleRect(element->getRect(), NULL);
                 } else {
                     GrAssert(Element::kPath_Type == element->getType());
-                    if (canRenderDirectToStencil) {
-                        *drawState->stencil() = gDrawToStencil;
-                        pr->drawPath(*clipPath, stroke, fGpu, false);
-                    } else {
-                        pr->stencilPath(*clipPath, stroke, fGpu);
+                    if (!clipPath->isEmpty()) {
+                        if (canRenderDirectToStencil) {
+                            *drawState->stencil() = gDrawToStencil;
+                            pr->drawPath(*clipPath, stroke, fGpu, false);
+                        } else {
+                            pr->stencilPath(*clipPath, stroke, fGpu);
+                        }
                     }
                 }
             }
 
             // now we modify the clip bit by rendering either the clip
             // element directly or a bounding rect of the entire clip.
             drawState->enableState(GrGpu::kModifyStencilClip_StateBit);
             for (int p = 0; p < passes; ++p) {
                 *drawState->stencil() = stencilSettings[p];
                 if (canDrawDirectToClip) {
@@ skipping 293 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 void GrClipMaskManager::releaseResources() {
     fAACache.releaseResources();
 }
 
 void GrClipMaskManager::setGpu(GrGpu* gpu) {
     fGpu = gpu;
     fAACache.setContext(gpu->getContext());
 }