Add support for AsyncContext in dispatching Events

dom.bs

@@ -1270,8 +1270,9 @@ property of the event being dispatched.
 <h3 id=dispatching-events>Dispatching events</h3>
 
 <p>To <dfn export id=concept-event-dispatch>dispatch</dfn> an <var>event</var> to a
-<var>target</var>, with an optional <var>legacy target override flag</var> and an optional
-<var>legacyOutputDidListenersThrowFlag</var>, run these steps:
+<var>target</var>, with an optional <var>legacy target override flag</var>, an optional
+<var>legacyOutputDidListenersThrowFlag</var>, and an optional
+<var>useCallerAsyncContextFlag</var>, run these steps:
 
 <ol>
  <li><p>Set <var>event</var>'s <a>dispatch flag</a>.
@@ -1408,8 +1409,9 @@ property of the event being dispatched.
  <li><p>Otherwise, set <var>event</var>'s {{Event/eventPhase}} attribute to
  {{Event/CAPTURING_PHASE}}.
 
- <li><p><a>Invoke</a> with <var>struct</var>, <var>event</var>, "<code>capturing</code>", and
- <var>legacyOutputDidListenersThrowFlag</var> if given.
+ <li><p><a>Invoke</a> with <var>struct</var>, <var>event</var>, "<code>capturing</code>",
+ <var>legacyOutputDidListenersThrowFlag</var> if given, and
+ <var>useCallerAsyncContextFlag</var> if given.
  </ol>
 
  <li>
@@ -1429,8 +1431,9 @@ property of the event being dispatched.
  <li><p>Set <var>event</var>'s {{Event/eventPhase}} attribute to {{Event/BUBBLING_PHASE}}.
  </ol>
 
- <li><p><a>Invoke</a> with <var>struct</var>, <var>event</var>, "<code>bubbling</code>", and
- <var>legacyOutputDidListenersThrowFlag</var> if given.
+ <li><p><a>Invoke</a> with <var>struct</var>, <var>event</var>, "<code>bubbling</code>",
+ <var>legacyOutputDidListenersThrowFlag</var> if given, and
+ <var>useCallerAsyncContextFlag</var> if given.
  </ol>
  </ol>
 
@@ -1496,8 +1499,9 @@ steps:</p>
 </ol>
 
 <p>To <dfn noexport id=concept-event-listener-invoke>invoke</dfn>, given a <var>struct</var>,
-<var>event</var>, <var>phase</var>, and an optional <var>legacyOutputDidListenersThrowFlag</var>,
-run these steps:
+<var>event</var>, <var>phase</var>, an optional <var>legacyOutputDidListenersThrowFlag</var>,
+an optional <var>legacyOutputDidListenersThrowFlag</var> if given, and an optional
+<var>useCallerAsyncContextFlag</var>, run these steps:
 
 <ol>
  <li><p>Set <var>event</var>'s <a for=Event>target</a> to the
@@ -1527,8 +1531,9 @@ run these steps:
  <a for=Event/path>invocation-target-in-shadow-tree</a>.
 
  <li><p>Let <var>found</var> be the result of running <a>inner invoke</a> with <var>event</var>,
- <var>listeners</var>, <var>phase</var>, <var>invocationTargetInShadowTree</var>, and
- <var>legacyOutputDidListenersThrowFlag</var> if given.
+ <var>listeners</var>, <var>phase</var>, <var>invocationTargetInShadowTree</var>,
+ <var>legacyOutputDidListenersThrowFlag</var> if given, and <var>useCallerAsyncContextFlag</var> if
+ given.
 
  <li>
  <p>If <var>found</var> is false and <var>event</var>'s {{Event/isTrusted}} attribute is true,
@@ -1553,20 +1558,24 @@ run these steps:
  </table>
 
  <li><p><a>Inner invoke</a> with <var>event</var>, <var>listeners</var>, <var>phase</var>,
- <var>invocationTargetInShadowTree</var>, and <var>legacyOutputDidListenersThrowFlag</var>
- if given.
+ <var>invocationTargetInShadowTree</var>, <var>legacyOutputDidListenersThrowFlag</var> if given,
+ and <var>useCallerAsyncContextFlag</var> if given.
 
  <li><p>Set <var>event</var>'s {{Event/type}} attribute value to <var>originalEventType</var>.
  </ol>
 </ol>
 
 <p>To <dfn noexport id=concept-event-listener-inner-invoke>inner invoke</dfn>, given an
 <var>event</var>, <var>listeners</var>, <var>phase</var>, <var>invocationTargetInShadowTree</var>,
-and an optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
+and an optional <var>legacyOutputDidListenersThrowFlag</var>, and an optional
+<var>useCallerAsyncContextFlag</var>, run these steps:
 
 <ol>
  <li><p>Let <var>found</var> be false.
 
+ <li><p>Let <var>useCreationTimeAsyncContext</var> be false if
+ <var>useCallerAsyncContextFlag</var> is passed and true otherwise.
+
  <li>
  <p><a for=list>For each</a> <var>listener</var> in <var>listeners</var>, whose
  <a for="event listener">removed</a> is false:
@@ -1609,8 +1618,9 @@ and an optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
 
  <li>
  <p><a>Call a user object's operation</a> with <var>listener</var>'s
- <a for="event listener">callback</a>, "<code>handleEvent</code>", « <var>event</var> », and
- <var>event</var>'s {{Event/currentTarget}} attribute value. If this throws an exception, then:
+ <a for="event listener">callback</a>, "<code>handleEvent</code>", « <var>event</var> »,
+ <var>event</var>'s {{Event/currentTarget}} attribute value, and
+ <var>useCreationTimeAsyncContext</var>. If this throws an exception, then:
 
  <ol>
  <li><p><a>Report the exception</a>.
@@ -1639,7 +1649,8 @@ and an optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
 
 <p>To <dfn export id=concept-event-fire>fire an event</dfn> named <var>e</var> at <var>target</var>,
 optionally using an <var>eventConstructor</var>, with a description of how IDL attributes are to be
-initialized, and a <var>legacy target override flag</var>, run these steps:
+initialized, a <var>legacy target override flag</var>, and an optional
+<var>useCallerAsyncContextFlag</var> run these steps:
 
 <ol>
  <li><p>If <var>eventConstructor</var> is not given, then let <var>eventConstructor</var> be
@@ -1657,7 +1668,8 @@ initialized, and a <var>legacy target override flag</var>, run these steps:
  <p class=note>This also allows for the {{Event/isTrusted}} attribute to be set to false.
 
  <li><p>Return the result of <a>dispatching</a> <var>event</var> at <var>target</var>, with
- <var>legacy target override flag</var> set if set.
+ <var>legacy target override flag</var> set if set, and <var>useCallerAsyncContextFlag</var> set if
+ set.
 </ol>
 
 <p class=note>Fire in the context of DOM is short for