Speculative fix for Chrome bug

https://codereview.appspot.com/6632045/



git-svn-id: http://skia.googlecode.com/svn/trunk@5855 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index d702031..32e6346 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -570,7 +570,8 @@
 void GrContext::setClip(const GrClipData* clipData) {
     fGpu->setClip(clipData);
 
-    fDrawState->setState(GrDrawState::kClip_StateBit, !clipData->fClipStack->isWideOpen());
+    fDrawState->setState(GrDrawState::kClip_StateBit, 
+                         clipData->fClipStack && !clipData->fClipStack->isWideOpen());
 }
 
 ////////////////////////////////////////////////////////////////////////////////