[editorial] dfn worker's outside/inside port, and clarify event retargeting

source

@@ -120449,17 +120449,15 @@ enum <dfn enum>WorkerType</dfn> { "classic", "module" };
 
   <div w-nodev>
 
+  <p>Each <code>Worker</code> object has an associated <dfn for="Worker">outside port</dfn> (a
+  <code>MessagePort</code>). This port is part of a channel that is set up when the worker is
+  created, but it is not exposed. This object must never be garbage collected before the
+  <code>Worker</code> object.</p>
+
   <p>The <dfn method for="Worker"><code data-x="dom-Worker-terminate">terminate()</code></dfn>
   method, when invoked, must cause the <span>terminate a worker</span> algorithm to be run on the
   worker with which the object is associated.</p>
 
-  <p><code>Worker</code> objects act as if they had an implicit <code>MessagePort</code> associated
-  with them. This port is part of a channel that is set up when the worker is created, but it is not
-  exposed. This object must never be garbage collected before the <code>Worker</code> object.</p>
-
-  <p>All messages received by that port must immediately be retargeted at the <code>Worker</code>
-  object.</p>
-
   <p>The <dfn method for="Worker"><code
   data-x="dom-Worker-postMessage">postMessage(<var>message</var>, <var>transfer</var>)</code></dfn>
   and <dfn method for="Worker"><code
@@ -120468,8 +120466,8 @@ enum <dfn enum>WorkerType</dfn> { "classic", "module" };
   they immediately invoked the respective <code
   data-x="dom-MessagePort-postMessage">postMessage(<var>message</var>, <var>transfer</var>)</code>
   and <code data-x="dom-MessagePort-postMessage-options">postMessage(<var>message</var>,
-  <var>options</var>)</code> on the port, with the same arguments, and returned the same return
-  value.</p>
+  <var>options</var>)</code> on <span>this</span>'s <span>outside port</span>, with the same
+  arguments, and returned the same return value.</p>
 
   </div>
 
@@ -120530,7 +120528,28 @@ enum <dfn enum>WorkerType</dfn> { "classic", "module" };
    <li><p>Let <var>outside port</var> be a <span>new</span> <code>MessagePort</code> in <var>outside
    settings</var>'s <span data-x="environment settings object's realm">realm</span>.</p></li>
 
-   <li><p>Associate the <var>outside port</var> with <var>worker</var>.</p></li>
+   <li><p>Set <var>worker</var>'s <span>outside port</span> to <var>outside port</var>.</p></li>
+
+   <li><p>Let <var>messageCallback</var> be the result of creating a Web IDL <code
+   data-x="dom-EventListener">EventListener</code> instance representing a reference to a function
+   of one argument <var>event</var> (a <span>MessageEvent</span>) that, when called, <span
+   data-x="concept-event-dispatch">dispatches</span> <var>event</var> at
+   <var>worker</var>.</p></li>
+
+   <li>
+    <p><span>Add an event listener</span> with <var>outside port</var> and a new <span>event
+    listener</span> whose <span data-x="event listener type">type</span> is "<code
+    data-x="event-message">message</code>" and <span data-x="event listener
+    callback">callback</span> is <var>messageCallback</var>.</p>
+
+    <p class="note">An <span>event listener</span> is different from an <code
+    data-x="dom-EventListener">EventListener</code>.</p>
+   </li>
+
+   <li><p><span>Add an event listener</span> with <var>outside port</var> and a new <span>event
+   listener</span> whose <span data-x="event listener type">type</span> is "<code
+   data-x="event-messageerror">messageerror</code>" and <span data-x="event listener
+   callback">callback</span> is <var>messageCallback</var>.</p></li>
 
    <li>
     <p>Run this step <span>in parallel</span>:</p>