Remove ancestor walk for non-SVG RenderObjects in willBeRemovedFromTree()

Source/core/rendering/svg/RenderSVGModelObject.h

Index: Source/core/rendering/svg/RenderSVGModelObject.h
diff --git a/Source/core/rendering/svg/RenderSVGModelObject.h b/Source/core/rendering/svg/RenderSVGModelObject.h
index c8df10aca7d8681f7e6cf6ec5d47511d7223ea4d..9b4ce1e103f52b031b6f64657824cc633eaf4305 100644
--- a/Source/core/rendering/svg/RenderSVGModelObject.h
+++ b/Source/core/rendering/svg/RenderSVGModelObject.h
@@ -67,6 +67,8 @@ public:
 
     SVGElement* element() const { return toSVGElement(RenderObject::node()); }
 
+    virtual bool isSVG() const OVERRIDE FINAL { return true; }
+
 protected:
     virtual void addLayerHitTestRects(LayerHitTestRects&, const RenderLayer* currentCompositedLayer, const LayoutPoint& layerOffset, const LayoutRect& containerRect) const OVERRIDE;
     virtual void willBeDestroyed();