Introduce toSVGFESpecularLightingElement(), and use it

Source/core/svg/SVGFESpecularLightingElement.h

Index: Source/core/svg/SVGFESpecularLightingElement.h
diff --git a/Source/core/svg/SVGFESpecularLightingElement.h b/Source/core/svg/SVGFESpecularLightingElement.h
index 3e10c9df99cfb966109772dee81b5cdf3bc3b5fc..63d63d38ef7d8830e12bcc7724355387ed60085f 100644
--- a/Source/core/svg/SVGFESpecularLightingElement.h
+++ b/Source/core/svg/SVGFESpecularLightingElement.h
@@ -22,6 +22,7 @@
 #ifndef SVGFESpecularLightingElement_h
 #define SVGFESpecularLightingElement_h
 
+#include "SVGNames.h"
 #include "core/platform/graphics/filters/FESpecularLighting.h"
 #include "core/svg/SVGAnimatedNumber.h"
 #include "core/svg/SVGFELightElement.h"
@@ -56,6 +57,12 @@ private:
     END_DECLARE_ANIMATED_PROPERTIES
 };
 
+inline SVGFESpecularLightingElement* toSVGFESpecularLightingElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::feSpecularLightingTag));
+    return static_cast<SVGFESpecularLightingElement*>(node);
+}
+
 } // namespace WebCore
 
 #endif