[SVG] SVGAnimatedString{,List} migration to new SVG property impl.

Source/core/svg/SVGImageElement.h

Index: Source/core/svg/SVGImageElement.h
diff --git a/Source/core/svg/SVGImageElement.h b/Source/core/svg/SVGImageElement.h
index adf5e7812b855df33af0cd5e1340a29dea00eeb6..ebc0f0f8392cc3e17ce57df2c12c899195c7e98e 100644
--- a/Source/core/svg/SVGImageElement.h
+++ b/Source/core/svg/SVGImageElement.h
@@ -43,11 +43,13 @@ public:
     SVGAnimatedLength* width() const { return m_width.get(); }
     SVGAnimatedLength* height() const { return m_height.get(); }
     SVGAnimatedPreserveAspectRatio* preserveAspectRatio() { return m_preserveAspectRatio.get(); }
+    SVGAnimatedString* href() { return m_href.get(); }
+    const SVGAnimatedString* href() const { return m_href.get(); }
 
 private:
     explicit SVGImageElement(Document&);
 
-    virtual bool isStructurallyExternal() const OVERRIDE { return !hrefCurrentValue().isNull(); }
+    virtual bool isStructurallyExternal() const OVERRIDE { return !href()->currentValue()->value().isNull(); }
     virtual bool supportsFocus() const OVERRIDE { return hasFocusEventListeners(); }
 
     bool isSupportedAttribute(const QualifiedName&);
@@ -73,8 +75,8 @@ private:
     RefPtr<SVGAnimatedLength> m_width;
     RefPtr<SVGAnimatedLength> m_height;
     RefPtr<SVGAnimatedPreserveAspectRatio> m_preserveAspectRatio;
+    RefPtr<SVGAnimatedString> m_href;
     BEGIN_DECLARE_ANIMATED_PROPERTIES(SVGImageElement)
-        DECLARE_ANIMATED_STRING(Href, href)
     END_DECLARE_ANIMATED_PROPERTIES
 
     SVGImageLoader m_imageLoader;