remove callback comment as that's added by #614

Author: annevk

dom.bs

@@ -798,10 +798,6 @@ method must, when invoked, run these steps:
 
 <h3 id=constructing-events>Constructing events</h3>
 
-<!-- XXX We need to add a callback of sorts here to be able to set relatedTarget and
-     touch target list properly. This is also needed for KeyboardEvent for some things and perhaps
-     more... -->
-
 <p>When a <dfn export for=Event id=concept-event-constructor>constructor</dfn> of the {{Event}}
 interface, or of an interface that inherits from the {{Event}} interface, is invoked, these steps
 must be run, given the arguments <var>type</var> and <var>eventInitDict</var>: