Enable stencil clipping in mixed sampled render targets

include/gpu/GrRenderTarget.h

Index: include/gpu/GrRenderTarget.h
diff --git a/include/gpu/GrRenderTarget.h b/include/gpu/GrRenderTarget.h
index 2309dbd876f6cf4e9d58b715730088045e83fb65..17d75d75290223bfca3f75a22256af8c189c56b7 100644
--- a/include/gpu/GrRenderTarget.h
+++ b/include/gpu/GrRenderTarget.h
@@ -81,6 +81,13 @@ public:
     }
 
     /**
+     * @return the number of actual raster samples-per-pixel, or zero if non-MSAA.
+     */
+    int numRasterSamples() const {
+        return fStencilAttachment ? this->numStencilSamples() : this->numColorSamples();
+    }
+
+    /**
      * @return true if the surface is mixed sampled, false otherwise.
      */
     bool hasMixedSamples() const {