Editorial: add a comma

source

@@ -90658,7 +90658,7 @@ document.body.appendChild(frame)</pre>
     <code>Document</code> object on which the method was invoked.</p>
 
     <p class="note">This basically causes <code data-x="dom-document-open">document.open()</code> to
-    be ignored when it's called from a <code data-x="event-beforeunload">beforeunload</code> <code
+    be ignored when it's called from a <code data-x="event-beforeunload">beforeunload</code>, <code
     data-x="event-pagehide">pagehide</code>, or <code data-x="event-unload">unload</code> event
     handler while the <code>Document</code> is being unloaded.</p>