Tidy finds WebIDLs with no spec.

Closes #6689

components/script/dom/webidls/WebSocket.webidl

@@ -2,6 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+// https://w3c.github.io/websockets/#the-websocket-interface
+
 enum BinaryType { "blob", "arraybuffer" };
 
 [Constructor(DOMString url)]