Have SVGURIReference API deal with Document references, not pointers

Source/core/rendering/svg/RenderSVGResourceContainer.h

Index: Source/core/rendering/svg/RenderSVGResourceContainer.h
diff --git a/Source/core/rendering/svg/RenderSVGResourceContainer.h b/Source/core/rendering/svg/RenderSVGResourceContainer.h
index a2e4bd15f24dbc3887732fb33a17a0e312af4b4a..5f1acf8220e3f8ead1d0933d8af4e4560487278f 100644
--- a/Source/core/rendering/svg/RenderSVGResourceContainer.h
+++ b/Source/core/rendering/svg/RenderSVGResourceContainer.h
@@ -75,19 +75,19 @@ private:
     HashSet<RenderLayer*> m_clientLayers;
 };
 
-inline RenderSVGResourceContainer* getRenderSVGResourceContainerById(Document* document, const AtomicString& id)
+inline RenderSVGResourceContainer* getRenderSVGResourceContainerById(Document& document, const AtomicString& id)
 {
     if (id.isEmpty())
         return 0;
 
-    if (RenderSVGResourceContainer* renderResource = document->accessSVGExtensions()->resourceById(id))
+    if (RenderSVGResourceContainer* renderResource = document.accessSVGExtensions()->resourceById(id))
         return renderResource;
 
     return 0;
 }
 
 template<typename Renderer>
-Renderer* getRenderSVGResourceById(Document* document, const AtomicString& id)
+Renderer* getRenderSVGResourceById(Document& document, const AtomicString& id)
 {
     if (RenderSVGResourceContainer* container = getRenderSVGResourceContainerById(document, id))
         return container->cast<Renderer>();