Speculative fix for Chrome bug in SkClipStack::isWideOpen

https://codereview.appspot.com/6743048/



git-svn-id: http://skia.googlecode.com/svn/trunk@6019 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 1ea2906..81f9717 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -569,7 +569,7 @@
     fGpu->setClip(clipData);
 
     fDrawState->setState(GrDrawState::kClip_StateBit,
-                         clipData->fClipStack && !clipData->fClipStack->isWideOpen());
+                         clipData && clipData->fClipStack && !clipData->fClipStack->isWideOpen());
 }
 
 ////////////////////////////////////////////////////////////////////////////////