Fix Window's close(d) members

close() needed to queue a task to close, though closed needs to immediately know when close() is invoked too.

Tests: web-platform-tests/wpt#15561 & web-platform-tests/wpt#15649.

Fixes #4405. Helps with #4363.

source

@@ -77111,6 +77111,9 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
   <p>A <span>browsing context</span> has a <dfn id="disowned-its-opener">disowned</dfn> boolean. It
   is initially false.</p>
 
+  <p>A <span>browsing context</span> has an <dfn>is closing</dfn> boolean. It is initially
+  false.</p>
+
   <p>A <span>browsing context</span> has a <span>session history</span>, which lists the
   <code>Document</code> objects that the <span>browsing context</span> has presented, is presenting,
   or will present. A <span>browsing context</span>'s <dfn data-export="">active document</dfn> is
@@ -78845,8 +78848,7 @@ dictionary <dfn>WindowPostMessageOptions</dfn> : <span>PostMessageOptions</span>
 
   <hr>
 
-  <p>The <dfn><code data-x="dom-name">name</code></dfn> attribute's getter, when invoked, must run
-  these steps:</p>
+  <p>The <dfn><code data-x="dom-name">name</code></dfn> attribute's getter must run these steps:</p>
 
   <ol>
    <li><p>If this <code>Window</code> object's <span data-x="window bc">browsing context</span> is
@@ -78856,8 +78858,7 @@ dictionary <dfn>WindowPostMessageOptions</dfn> : <span>PostMessageOptions</span>
    context</span>'s <span data-x="browsing context name">name</span>.</p></li>
   </ol>
 
-  <p>The <code data-x="dom-name">name</code> attribute's setter, when invoked, must run these
-  steps:</p>
+  <p>The <code data-x="dom-name">name</code> attribute's setter must run these steps:</p>
 
   <ol>
    <li><p>If this <code>Window</code> object's <span data-x="window bc">browsing context</span> is
@@ -78872,35 +78873,50 @@ dictionary <dfn>WindowPostMessageOptions</dfn> : <span>PostMessageOptions</span>
 
   <hr>
 
-  <p>The <dfn><code data-x="dom-window-close">close()</code></dfn> method on <code>Window</code>
-  objects should, if all the following conditions are met, <span data-x="close a browsing
-  context">close</span> the <span>browsing context</span> <var>A</var>:
+  <p>The <dfn><code data-x="dom-window-close">close()</code></dfn> method must run these steps:
 
-  <ul class="brief">
+  <ol>
+   <li><p>Let <var>current</var> be this <code>Window</code> object's <span data-x="window
+   bc">browsing context</span>.</p></li>
+
+   <li><p>If <var>current</var> is null or its <span>is closing</span> is true, then
+   return.</p></li>
+
+   <li>
+    <p>If all the following are true</p>
+
+    <ul class="brief">
+     <li><var>current</var> is <span>script-closable</span></li>
 
-   <li>The corresponding <span>browsing context</span> <var>A</var> is
-   <span>script-closable</span>.</li>
+     <li>the <span>incumbent settings object</span>'s <span>responsible browsing context</span> is
+     <span>familiar with</span> <var>current</var> </li>
 
-   <li>The <span>responsible browsing context</span> specified by the <span>incumbent settings
-   object</span> is <span>familiar with</span> the <span>browsing context</span> <var>A</var>.</li>
+     <li id="sandboxClose">the <span>incumbent settings object</span>'s <span>responsible browsing
+     context</span> is <span>allowed to navigate</span> <var>current</var></li>
+    </ul>
 
-   <li id="sandboxClose">The <span>responsible browsing context</span> specified by the
-   <span>incumbent settings object</span> is <span>allowed to navigate</span> the <span>browsing
-   context</span> <var>A</var>.</li>
+    <p>then:</p>
 
-  </ul>
+    <ol>
+     <li><p>Set <var>current</var>'s <span>is closing</span> to true.</p></li>
+
+     <li><p><span>Queue a task</span> on the <span>DOM manipulation task source</span> to <span
+     data-x="close a browsing context">close</span> <var>current</var>.</p></li>
+    </ol>
+   </li>
+  </ol>
 
   <p>A <span>browsing context</span> is <dfn>script-closable</dfn> if it is an <span>auxiliary
   browsing context</span> that was created by a script (as opposed to by an action of the user), or
   if it is a <span>top-level browsing context</span> whose <span>session history</span> contains
   only one <code>Document</code>.</p>
 
-  <p>The <dfn><code data-x="dom-window-closed">closed</code></dfn> attribute on <code>Window</code>
-  objects must return true if the <code>Window</code> object's <span>browsing context</span> has
-  been <span data-x="a browsing context is discarded">discarded</span>, and false otherwise.</p>
+  <p>The <dfn><code data-x="dom-window-closed">closed</code></dfn> attribute's getter must return
+  true if this <code>Window</code> object's <span data-x="window bc">browsing context</span> is
+  null or its <span>is closing</span> is true, and false otherwise.</p>
 
-  <p>The <dfn><code data-x="dom-window-stop">stop()</code></dfn> method on <code>Window</code>
-  objects must <span>stop document loading</span> given this <code>Window</code> object's <span
+  <p>The <dfn><code data-x="dom-window-stop">stop()</code></dfn> method must <span>stop document
+  loading</span> given this <code>Window</code> object's <span
   data-x="concept-document-window">associated <code>Document</code></span>.</p>
 
   </div>