Introduce toSVGEllipseElement(), and use it

Source/core/svg/SVGEllipseElement.h

Index: Source/core/svg/SVGEllipseElement.h
diff --git a/Source/core/svg/SVGEllipseElement.h b/Source/core/svg/SVGEllipseElement.h
index c341e14860558456a524d51f10485d0772c470d9..8d98e1074f792701c9c6cd8c3c1ba21750b81f37 100644
--- a/Source/core/svg/SVGEllipseElement.h
+++ b/Source/core/svg/SVGEllipseElement.h
@@ -21,6 +21,7 @@
 #ifndef SVGEllipseElement_h
 #define SVGEllipseElement_h
 
+#include "SVGNames.h"
 #include "core/svg/SVGAnimatedBoolean.h"
 #include "core/svg/SVGAnimatedLength.h"
 #include "core/svg/SVGExternalResourcesRequired.h"
@@ -56,6 +57,12 @@ private:
     END_DECLARE_ANIMATED_PROPERTIES
 };
 
+inline SVGEllipseElement* toSVGEllipseElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::ellipseTag));
+    return static_cast<SVGEllipseElement*>(node);
+}
+
 } // namespace WebCore
 
 #endif