Sync the DocumentType interface with the spec

Source/core/dom/DocumentType.idl

Index: Source/core/dom/DocumentType.idl
diff --git a/Source/core/dom/DocumentType.idl b/Source/core/dom/DocumentType.idl
index 680352bc1b6e4283498cd28361a82679633273c6..1b7f41128f82eafa6ffa9b2a86a14aeadbb08c94 100644
--- a/Source/core/dom/DocumentType.idl
+++ b/Source/core/dom/DocumentType.idl
@@ -17,14 +17,10 @@
  * Boston, MA 02110-1301, USA.
  */
 
-interface DocumentType : Node {
-
-    // DOM Level 1
+// https://dom.spec.whatwg.org/#interface-documenttype
 
+interface DocumentType : Node {
     readonly attribute DOMString name;
-
-    // DOM Level 2
-
     readonly attribute DOMString publicId;
     readonly attribute DOMString systemId;
 };