Add UseCounter for SVGURIReference.href.baseVal/animVal.

Source/core/svg/SVGAnimatedString.h

Index: Source/core/svg/SVGAnimatedString.h
diff --git a/Source/core/svg/SVGAnimatedString.h b/Source/core/svg/SVGAnimatedString.h
index 636a04f18da4a333756201a26309f95deb9f8962..e9da37c31ad8255101f6ec00d293fc6cb282e61f 100644
--- a/Source/core/svg/SVGAnimatedString.h
+++ b/Source/core/svg/SVGAnimatedString.h
@@ -44,6 +44,10 @@ public:
         return adoptRefWillBeNoop(new SVGAnimatedString(contextElement, attributeName, initialValue));
     }
 
+    String baseVal();
+    void setBaseVal(String, ExceptionState&);
+    String animVal();
+
 protected:
     SVGAnimatedString(SVGElement* contextElement, const QualifiedName& attributeName, PassRefPtrWillBeRawPtr<SVGString> initialValue)
         : SVGAnimatedProperty<SVGString>(contextElement, attributeName, initialValue)