Use DEFINE_NODE_TYPE_CASTS_WITH_FUNCTION to generate toSVGSMILElement()

Source/core/svg/SVGAElement.cpp

Index: Source/core/svg/SVGAElement.cpp
diff --git a/Source/core/svg/SVGAElement.cpp b/Source/core/svg/SVGAElement.cpp
index e1d97847138fad169c38303ecf3e332b58f8db9c..55901441d024a266cb3e7c4f517fef64201f2af3 100644
--- a/Source/core/svg/SVGAElement.cpp
+++ b/Source/core/svg/SVGAElement.cpp
@@ -162,7 +162,7 @@ void SVGAElement::defaultEventHandler(Event* event)
 
             if (url[0] == '#') {
                 Element* targetElement = treeScope().getElementById(url.substring(1));
-                if (SVGSMILElement::isSMILElement(targetElement)) {
+                if (targetElement && isSVGSMILElement(*targetElement)) {
                     toSVGSMILElement(targetElement)->beginByLinkActivation();
                     event->setDefaultHandled();
                     return;