[SVG] SVGAnimatedRect migration to new SVG property impl.

Source/core/svg/SVGSymbolElement.h

Index: Source/core/svg/SVGSymbolElement.h
diff --git a/Source/core/svg/SVGSymbolElement.h b/Source/core/svg/SVGSymbolElement.h
index f5f4954b57e3efd2ff5f06c73039a9c6bb078565..a1d6e1ec196ca2a887aed766a7e0a06615829a8a 100644
--- a/Source/core/svg/SVGSymbolElement.h
+++ b/Source/core/svg/SVGSymbolElement.h
@@ -34,6 +34,8 @@ class SVGSymbolElement FINAL : public SVGElement,
 public:
     static PassRefPtr<SVGSymbolElement> create(Document&);
 
+    SVGAnimatedRect* viewBox() const { return m_viewBox.get(); }
+
 private:
     explicit SVGSymbolElement(Document&);
 
@@ -47,8 +49,8 @@ private:
 
     virtual bool selfHasRelativeLengths() const OVERRIDE;
 
+    RefPtr<SVGAnimatedRect> m_viewBox;
     BEGIN_DECLARE_ANIMATED_PROPERTIES(SVGSymbolElement)
-        DECLARE_ANIMATED_RECT(ViewBox, viewBox)
         DECLARE_ANIMATED_PRESERVEASPECTRATIO(PreserveAspectRatio, preserveAspectRatio)
     END_DECLARE_ANIMATED_PROPERTIES
 };