[cssom-view-1] Switch to constructor() method syntax.

Author: tabatkins

cssom-view-1/Overview.bs

@@ -825,9 +825,9 @@ as <a>event handler IDL attributes</a>, by all objects implementing the {{MediaQ
 </table>
 
 <pre class=idl>
-[Exposed=Window,
- Constructor(CSSOMString type, optional MediaQueryListEventInit eventInitDict = {})]
+[Exposed=Window]
 interface MediaQueryListEvent : Event {
+  constructor(CSSOMString type, optional MediaQueryListEventInit eventInitDict = {});
   readonly attribute CSSOMString media;
   readonly attribute boolean matches;
 };