Use toSVGFontElement() instead of static_cast<SVGFontElement*>

Source/core/svg/SVGFontElement.h

Index: Source/core/svg/SVGFontElement.h
diff --git a/Source/core/svg/SVGFontElement.h b/Source/core/svg/SVGFontElement.h
index 92c2a5460a37040ae54b4def0f9168f0ea7d69b8..ff9ae3a2e60c5a6e5fcf6e15f7f299181ce61056 100644
--- a/Source/core/svg/SVGFontElement.h
+++ b/Source/core/svg/SVGFontElement.h
@@ -23,6 +23,7 @@
 #define SVGFontElement_h
 
 #if ENABLE(SVG_FONTS)
+#include "SVGNames.h"
 #include "core/svg/SVGAnimatedBoolean.h"
 #include "core/svg/SVGExternalResourcesRequired.h"
 #include "core/svg/SVGGlyphMap.h"
@@ -88,6 +89,12 @@ private:
     bool m_isGlyphCacheValid;
 };
 
+inline SVGFontElement* toSVGFontElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::fontTag));
+    return static_cast<SVGFontElement*>(node);
+}
+
 } // namespace WebCore
 
 #endif // ENABLE(SVG_FONTS)