Support subtitles for native fullscreen video

Source/core/rendering/RenderLayerModelObject.cpp

Index: Source/core/rendering/RenderLayerModelObject.cpp
diff --git a/Source/core/rendering/RenderLayerModelObject.cpp b/Source/core/rendering/RenderLayerModelObject.cpp
index dda32af59dab25d9f440955a0cb53b3aeee5d6ab..2019c7c78534c25db61270a7623c352b651fdc24 100644
--- a/Source/core/rendering/RenderLayerModelObject.cpp
+++ b/Source/core/rendering/RenderLayerModelObject.cpp
@@ -206,5 +206,10 @@ void RenderLayerModelObject::addLayerHitTestRects(LayerHitTestRects& rects, cons
     }
 }
 
+RenderLayerBacking* RenderLayerModelObject::backing() const
+{
+    return m_layer ? m_layer->backing() : 0;
+}
+
 } // namespace WebCore