Use the DOM manipulation task source for promise-related events

Fixes #3731.

source

@@ -89475,7 +89475,8 @@ dictionary <dfn>ErrorEventInit</dfn> : <span>EventInit</span> {
 
    <li>
 
-    <p><span>Queue a task</span> to run the following substep:</p>
+    <p><span>Queue a task</span> on the <span>DOM manipulation task source</span> to run the following
+    substep:</p>
 
     <ol>
 
@@ -89558,14 +89559,14 @@ dictionary <dfn>ErrorEventInit</dfn> : <span>EventInit</span> {
      <li><p>Remove <var>promise</var> from <var>settings object</var>'s <span>outstanding rejected
      promises weak set</span>.</p></li>
 
-     <li><p><span>Queue a task</span> to <span data-x="concept-event-fire">fire an event</span>
-     named <code data-x="event-rejectionhandled">rejectionhandled</code> at <var>settings
-     object</var>'s <span data-x="concept-settings-object-global">global object</span>, using
-     <code>PromiseRejectionEvent</code>, with the <code
-     data-x="dom-PromiseRejectionEvent-promise">promise</code> attribute initialized to
-     <var>promise</var>, and the <code data-x="dom-PromiseRejectionEvent-reason">reason</code>
-     attribute initialized to the value of <var>promise</var>'s [[PromiseResult]] internal
-     slot.</p></li>
+     <li><p><span>Queue a task</span> on the <span>DOM manipulation task source</span> to <span
+    data-x="concept-event-fire">fire an event</span> named <code
+    data-x="event-rejectionhandled">rejectionhandled</code> at <var>settings object</var>'s <span
+    data-x="concept-settings-object-global">global object</span>, using
+    <code>PromiseRejectionEvent</code>, with the <code
+    data-x="dom-PromiseRejectionEvent-promise">promise</code> attribute initialized to
+    <var>promise</var>, and the <code data-x="dom-PromiseRejectionEvent-reason">reason</code> attribute
+    initialized to the value of <var>promise</var>'s [[PromiseResult]] internal slot.</p></li>
 
     </ol>
    </li>