Fix window.close() always doing nothing

This regressed in af3ff83, which intended to allow other specifications to call "close a top-level traversable" without interfering with ongoing close operations due to window.close(). However, the way it did so was buggy. Fix it.

Additionally, export "close" for top-level traversables, and update the editorial style for how "close" and "destroy" are declared for top-level traversables.

Fixes #10678.

source

@@ -89791,7 +89791,8 @@ dictionary <dfn dictionary>WindowPostMessageOptions</dfn> : <span>StructuredSeri
      <li><p>Set <var>thisTraversable</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 top-level traversable">close</span> <var>thisTraversable</var>.</p></li>
+     data-x="definitely close a top-level traversable">definitely close</span>
+     <var>thisTraversable</var>.</p></li>
     </ol>
    </li>
   </ol>
@@ -96837,8 +96838,8 @@ interface <dfn interface>NotRestoredReasons</dfn> {
    <li><p>Invoke <span>WebDriver BiDi navigable destroyed</span> with <var>navigable</var>.</p></li>
   </ol>
 
-  <p>To <dfn>destroy a top-level traversable</dfn> given a <span>top-level traversable</span>
-  <var>traversable</var>:</p>
+  <p>To <dfn data-x="destroy a top-level traversable">destroy</dfn> a <span>top-level
+  traversable</span> <var>traversable</var>:</p>
 
   <ol>
    <li><p>Let <var>browsingContext</var> be <var>traversable</var>'s <span
@@ -96872,21 +96873,30 @@ interface <dfn interface>NotRestoredReasons</dfn> {
   <p>User agents may <span>destroy a top-level traversable</span> at any time (typically, <a
   href="#nav-traversal-ui">in response to user requests</a>).</p>
 
-  <p id="closing-browsing-contexts"><span id="close-a-browsing-context"></span>To <dfn>close a
-  top-level traversable</dfn> <var>traversable</var>:</p>
+  <p id="closing-browsing-contexts"><span id="close-a-browsing-context"></span>To <dfn export
+  id="close-a-top-level-traversable" for="top-level traversable" data-x="close a top-level
+  traversable">close</dfn> a <span>top-level traversable</span> <var>traversable</var>:</p>
 
   <ol>
    <li><p>If <var>traversable</var>'s <span>is closing</span> is true, then return.</p></li>
 
+   <li><p><span data-x="definitely close a top-level traversable">Definitely close</span>
+   <var>traversable</var>.</p></li>
+  </ol>
+
+  <p>To <dfn data-x="definitely close a top-level traversable">definitely close</dfn> a
+  <span>top-level traversable</span> <var>traversable</var>:</p>
+
+  <ol>
    <li><p>Let <var>toUnload</var> be <var>traversable</var>'s <span data-x="nav-document">active
    document</span>'s <span>inclusive descendant navigables</span>.</p></li>
 
    <li><p>If the result of <span>checking if unloading is canceled</span> for <var>toUnload</var> is
    true, then return.</p></li>
 
    <li>
-    <p><span data-x="tn-append-session-history-traversal-steps">Append the following session
-    history traversal steps</span> to <var>traversable</var>:</p>
+    <p><span data-x="tn-append-session-history-traversal-steps">Append the following session history
+    traversal steps</span> to <var>traversable</var>:</p>
 
     <ol>
      <li><p>Let <var>afterAllUnloads</var> be an algorithm step which <span data-x="destroy a
@@ -96898,6 +96908,12 @@ interface <dfn interface>NotRestoredReasons</dfn> {
    </li>
   </ol>
 
+  <p class="note">The <span data-x="close a top-level traversable">close</span> vs. <span
+  data-x="definitely close a top-level traversable">definitely close</span> separation allows other
+  specifications to call <span data-x="close a top-level traversable">close</span> and have it be a
+  no-op if the top-level traversable is already closing due to JavaScript code calling <code
+  data-x="dom-window-close">window.close()</code>.</p>
+
 
   <h5><span id="browsing-context-names"></span>Navigable target names</h5>