Introduce toSVGRectElement(), use it

Source/core/svg/SVGRectElement.h

Index: Source/core/svg/SVGRectElement.h
diff --git a/Source/core/svg/SVGRectElement.h b/Source/core/svg/SVGRectElement.h
index cd5b85c176b2c82635b505a8e7b6867b9763599e..26253fcce3fe6874cfd716d4224681a8b395c2ad 100644
--- a/Source/core/svg/SVGRectElement.h
+++ b/Source/core/svg/SVGRectElement.h
@@ -21,6 +21,7 @@
 #ifndef SVGRectElement_h
 #define SVGRectElement_h
 
+#include "SVGNames.h"
 #include "core/svg/SVGAnimatedBoolean.h"
 #include "core/svg/SVGAnimatedLength.h"
 #include "core/svg/SVGExternalResourcesRequired.h"
@@ -58,6 +59,12 @@ private:
     END_DECLARE_ANIMATED_PROPERTIES
 };
 
+inline SVGRectElement* toSVGRectElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::rectTag));
+    return static_cast<SVGRectElement*>(node);
+}
+
 } // namespace WebCore
 
 #endif