Apply current conventions for optional named parameters to fire an event. Fix grammar.

Author: dandclark

dom.bs

@@ -1360,15 +1360,15 @@ property of the event being dispatched.
 
 <div algorithm>
 <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> (default false) and an
+optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
 
 <ol>
  <li><p>Set <var>event</var>'s <a>dispatch flag</a>.
 
  <li>
   <p>Let <var>targetOverride</var> be <var>target</var>, if <var>legacy target override flag</var>
-  is not given, and <var>target</var>'s <a>associated <code>Document</code></a> otherwise.
+  is true, and <var>target</var>'s <a>associated <code>Document</code></a> otherwise.
   [[!HTML]]
 
   <p class=note><var>legacy target override flag</var> is only used by HTML and only when
@@ -1743,8 +1743,8 @@ and an optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
 <div algorithm>
 <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> and an optional <var>relatedTarget</var>,
-run these steps:
+initialized, an optional boolean <var>legacy target override flag</var> (default false), and an
+optional {{EventTarget}} <var>relatedTarget</var>:
 
 <ol>
  <li><p>If <var>eventConstructor</var> is not given, then let <var>eventConstructor</var> be
@@ -1755,17 +1755,17 @@ run these steps:
 
  <li><p>Initialize <var>event</var>'s {{Event/type}} attribute to <var>e</var>.
 
- <li><p>If <var>relatedTarget</var> is given, set <var>event</var>'s <a for=Event>relatedTarget</a>
- to <var>relatedTarget</var>.
+ <li><p>If <var>relatedTarget</var> is given, then set <var>event</var>'s <a
+ for=Event>relatedTarget</a> to <var>relatedTarget</var>.
 
  <li>
   <p>Initialize any other IDL attributes of <var>event</var> as described in the invocation of this
   algorithm.
 
   <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.
+ <li><p>Return the result of <a>dispatching</a> <var>event</var> at <var>target</var> with
+ <var>legacy target override flag</var>.
 </ol>
 </div>