fixup abort steps before event.

Author: mikewest

dom.bs

@@ -1483,8 +1483,8 @@ steps:
 <ol>
  <li>Let <var>signal</var> be this object's {{PromiseController/signal}}.
  <li>Set <var>signal</var>'s [=PromiseSignal/aborted flag=].
- <li>[=Fire an event=] named <code>abort</code> at <var>signal</var>.
  <li>Run <var>signal</var>'s [=PromiseSignal/abort steps=].
+ <li>[=Fire an event=] named <code>abort</code> at <var>signal</var>.
 </ol>
 
 <h4 id=interface-cancellationcontroller>Interface {{PromiseSignal}}</h4>