Expand <details> for find-in-page and element fragments

source

@@ -56988,6 +56988,18 @@ interface <dfn>HTMLDetailsElement</dfn> : <span>HTMLElement</span> {
  &lt;p>Direction: North&lt;/p>
 &lt;/details></code></pre>
 
+  <p>The <dfn>ancestor details revealing algorithm</dfn> is to run the following steps on
+  currentNode:</p>
+
+  <ol>
+   <li><p>While currentNode has a parent node, perform the following steps:</p></li>
+
+   <li><p>If currentNode is slotted into the second slot of a details element, add the <code
+   data-x="attr-details-open">open</code> attribute to the details element. Then, let currentNode
+   be the details element which was just opened. Otherwise, let currentNode be the parent node of
+   currentNode.</li></p>
+  </ol>
+
   </div>
 
 
@@ -75340,6 +75352,27 @@ body { display:none }
   can navigate through the <span data-x="fip-matches">matches</span> by advancing the <span
   data-x="fip-active-match">active match</span> using the <span>find-in-page interface</span>.</p>
 
+  <p>When find-in-page begins searching for matches, all <code>details</code> elements in the page
+  which are not <code data-x="attr-details-open">open</code> should have their second slot be added
+  to the rendering without modifying the <code data-x="attr-details-open">open</code> attribute.
+  After find-in-page finishes searching for matches, those details elements should have their second
+  slot be removed from the rendering again.</p>
+
+  <p>When find-in-page chooses a new <span data-x="fip-active-match">active match</span>, run the
+  <span>ancestor details revealing algorithm</span> on the first node in the <span
+  data-x="fip-active-match">active match</span>.
+
+  <p>When find-in-page chooses a new <span data-x="fip-active-match">active match</span>, perform
+  the following steps:</p>
+
+  <ol>
+    <li><p>Let node be the first node in the <span data-x="fip-active-match">active
+    match</span>.</p></li>
+
+    <li><p>Queue a global task on the user interaction task source given node's relevant global
+    object to run the <span>ancestor details revealing algorithm</span> on node.</p></li>
+  </ol>
+
   <p class="XXX"><a href="https://github.com/whatwg/html/issues/3539">Issue #3539</a> tracks
   standardizing how <span>find-in-page</span> underlies the currently-unspecified <code
   data-x="">window.find()</code> API.</p>
@@ -86015,6 +86048,8 @@ new PaymentRequest(&hellip;); // Allowed to use
      <li><p>Set the <code>Document</code>'s <span>target element</span> to
      <var>target</var>.</p></li>
 
+     <li><p>Run the <span>ancestor details revealing algorithm</span> on <var>target</var>.
+
      <li><p><span data-x="scroll an element into view">Scroll <var>target</var> into view</span>,
      with <var>behavior</var> set to "auto", <var>block</var> set to "start", and <var>inline</var>
      set to "nearest". <ref spec=CSSOMVIEW></p></li>