diff --git a/source b/source
index e4aed77eb44..c6fe89f0786 100644
--- a/source
+++ b/source
@@ -99976,6 +99976,22 @@ location.href = '#foo';</code></pre>
    data-x="window-navigation-api">navigation API</span>, <var>entriesForNavigationAPI</var>, and
    <var>reactivatedEntry</var>.</p></li>
 
+   <li><p>Let <var>window</var> be the <code>Window</code> whose <span data-x="concept-document-window">
+   associated <code>Document</code></span> is <var>document</var>.</p></li>
+
+   <li><p>Let <var>channels</var> be a list of <code>BroadcastChannel</code> objects whose
+   <span>relevant global object</span> is <var>window</var>.</p></li>
+
+   <li><p>Sort <var>channels</var> by the creation order, oldest first.</p></li>
+
+   <li><p>For each <var>channel</var> in <var>channels</var>:</p>
+    <ul>
+     <li><p>For each string <var>serialized</var> from <var>channel</var>'s <span>message queue</span>,
+     <span data-x="dom-BroadcastChannel-post-a-message">post a message</span> with <var>serialized</var>
+     to <var>channel</var>.</p></li>
+    </ul>
+   </li>
+
    <li>
     <p>If <var>document</var>'s <span>current document readiness</span> is "<code
     data-x="">complete</code>", and <var>document</var>'s <span>page showing</span> flag is false,
@@ -113696,8 +113712,9 @@ interface <dfn interface>BroadcastChannel</dfn> : <span>EventTarget</span> {
 
   <div w-nodev>
 
-  <p>A <code>BroadcastChannel</code> object has a <dfn>channel name</dfn> and a <dfn
-  data-x="concept-BroadcastChannel-closed">closed flag</dfn>.</p>
+  <p>A <code>BroadcastChannel</code> object has a <dfn>channel name</dfn>, a
+  <dfn data-x="concept-BroadcastChannel-closed">closed flag</dfn> and an initially empty <span>queue</span>
+  <dfn>message queue</dfn>.
 
   <p>The <dfn><code data-x="dom-BroadcastChannel">new BroadcastChannel(<var>name</var>)</code></dfn>
   constructor steps are:</p>
@@ -113725,6 +113742,37 @@ interface <dfn interface>BroadcastChannel</dfn> : <span>EventTarget</span> {
    <span>worker</span> is not a <span>suspendable worker</span>.</p></li>
   </ul>
 
+  <p>To <dfn data-x="dom-BroadcastChannel-post-a-message">post a serialized message</dfn>
+  given a string <var>serialized</var> and a <code>BroadcastChannel</code> <var>channel</var>,
+  run these steps:</p>
+
+  <ol>
+   <li><p>If <var>channel</var>'s <span data-x="concept-BroadcastChannel-closed">closed
+   flag</span> is true, then abort these steps.</p></li>
+
+   <li><p>Let <var>targetRealm</var> be <var>destination</var>'s <span
+   data-x="concept-relevant-realm">relevant realm</span>.</p></li>
+
+   <li>
+    <p>Let <var>data</var> be <span>StructuredDeserialize</span>(<var>serialized</var>,
+    <var>targetRealm</var>).</p>
+
+    <p>If this throws an exception, catch it, <span data-x="concept-event-fire">fire an
+    event</span> named <code data-x="event-messageerror">messageerror</code> at
+    <var>destination</var>, using <code>MessageEvent</code>, with the <code
+    data-x="dom-MessageEvent-origin">origin</code> attribute initialized to the <span
+    data-x="serialization of an origin">serialization</span> of <var>sourceOrigin</var>, and then
+    abort these steps.</p>
+   </li>
+
+   <li><p><span data-x="concept-event-fire">Fire an event</span> named <code
+   data-x="event-message">message</code> at <var>channel</var>, using <code>MessageEvent</code>,
+   with the <code data-x="dom-MessageEvent-data">data</code> attribute initialized to <var>data</var>
+   and the <code data-x="dom-MessageEvent-origin">origin</code> attribute initialized to the
+   <span data-x="serialization of an origin">serialization</span> of <var>sourceOrigin</var>.</p></li>
+  </ol>
+
+
   <p>The <dfn method for="BroadcastChannel"><code
   data-x="dom-BroadcastChannel-postMessage">postMessage(<var>message</var>)</code></dfn> method
   steps are:</p>
@@ -113751,8 +113799,6 @@ interface <dfn interface>BroadcastChannel</dfn> : <span>EventTarget</span> {
     match the following criteria:</p>
 
     <ul>
-     <li><p>They are <span>eligible for messaging</span>.</p></li>
-
      <li><p>The result of running <span>obtain a storage key for non-storage purposes</span> with
      their <span>relevant settings object</span> <span data-x="storage key equal">equals</span>
      <var>sourceStorageKey</var>.</p></li>
@@ -113764,6 +113810,31 @@ interface <dfn interface>BroadcastChannel</dfn> : <span>EventTarget</span> {
 
    <li><p>Remove <var>source</var> from <var>destinations</var>.</p></li>
 
+   <li>
+    <p>For each <var>destination</var> in <var>destinations</var>, if <var>destination</var> is
+    not <span>eligible for messaging</span>, perform the following steps:</p>
+    <ul>
+     <li>
+      <p>If <var>destination</var>'s <span>relevant global object</span> is a <code>Window</code>
+      <var>window</var>, <span>enqueue</span> <var>serialized</var> on <span>message queue</span>.</p>
+     </li>
+
+     <li>
+      <p>If the <span data-x="list size">size</span> of <var>destination</var>'s <span>message queue</span>
+      is above a certain threshold, the user agent may <span data-x="destroy a document">destroy</span>
+      <var>window</var>'s <span data-x="concept-document-window">associated <code>Document</code></span>.</p>
+
+      <p class="note">The user agents can set their own threshold (possibly 0) to trigger the
+      <code>Document</code> destruction.</p>
+
+      <p class="note">The <code>Document</code> to be destroyed here is not <span>fully active</span>
+      (either detached or in <a href="#note-bfcache">bfcache</a>).</p>
+     </li>
+
+     <li><p>Remove <var>destination</var> from <var>destinations</var>.</p></li>
+    </ul>
+   </li>
+
    <li><p>Sort <var>destinations</var> such that all <code>BroadcastChannel</code> objects whose
    <span data-x="relevant agent">relevant agents</span> are the same are sorted in creation order,
    oldest first. (This does not define a complete ordering. Within this constraint, user agents may
@@ -113772,34 +113843,8 @@ interface <dfn interface>BroadcastChannel</dfn> : <span>EventTarget</span> {
    <li>
     <p>For each <var>destination</var> in <var>destinations</var>, <span>queue a global task</span>
     on the <span>DOM manipulation task source</span> given <var>destination</var>'s <span>relevant
-    global object</span> to perform the following steps:</p>
-
-    <ol>
-     <li><p>If <var>destination</var>'s <span data-x="concept-BroadcastChannel-closed">closed
-     flag</span> is true, then abort these steps.</p></li>
-
-     <li><p>Let <var>targetRealm</var> be <var>destination</var>'s <span
-     data-x="concept-relevant-realm">relevant realm</span>.</p></li>
-
-     <li>
-      <p>Let <var>data</var> be <span>StructuredDeserialize</span>(<var>serialized</var>,
-      <var>targetRealm</var>).</p>
-
-      <p>If this throws an exception, catch it, <span data-x="concept-event-fire">fire an
-      event</span> named <code data-x="event-messageerror">messageerror</code> at
-      <var>destination</var>, using <code>MessageEvent</code>, with the <code
-      data-x="dom-MessageEvent-origin">origin</code> attribute initialized to the <span
-      data-x="serialization of an origin">serialization</span> of <var>sourceOrigin</var>, and then
-      abort these steps.</p>
-     </li>
-
-     <li><p><span data-x="concept-event-fire">Fire an event</span> named <code
-     data-x="event-message">message</code> at <var>destination</var>, using
-     <code>MessageEvent</code>, with the <code data-x="dom-MessageEvent-data">data</code> attribute
-     initialized to <var>data</var> and the <code data-x="dom-MessageEvent-origin">origin</code>
-     attribute initialized to the <span data-x="serialization of an origin">serialization</span> of
-     <var>sourceOrigin</var>.</p></li>
-    </ol>
+    global object</span> to <span data-x="dom-BroadcastChannel-post-a-message">post a message</span>
+    with <var>serialized</var> to <var>destination</var>.</p>
    </li>
   </ol>