Add SVGTests attrs to SVGSMILElement to support SVGDiscardElement

Source/core/svg/animation/SVGSMILElement.h

Index: Source/core/svg/animation/SVGSMILElement.h
diff --git a/Source/core/svg/animation/SVGSMILElement.h b/Source/core/svg/animation/SVGSMILElement.h
index fbce2168c0e6167073200e1b9b12d8f9dcc6401b..e83f0943954b485857f379b1cd233e103556dcff 100644
--- a/Source/core/svg/animation/SVGSMILElement.h
+++ b/Source/core/svg/animation/SVGSMILElement.h
@@ -28,6 +28,7 @@
 
 #include "core/SVGNames.h"
 #include "core/svg/SVGElement.h"
+#include "core/svg/SVGTests.h"
 #include "core/svg/animation/SMILTime.h"
 #include "platform/heap/Heap.h"
 #include "wtf/HashMap.h"
@@ -42,7 +43,7 @@ template<typename T> class EventSender;
 typedef EventSender<SVGSMILElement> SMILEventSender;
 
 // This class implements SMIL interval timing model as needed for SVG animation.
-class SVGSMILElement : public SVGElement {
+class SVGSMILElement : public SVGElement, public SVGTests {
 public:
     SVGSMILElement(const QualifiedName&, Document&);
     virtual ~SVGSMILElement();