Fixes to delegatesFocus

* Make it use the shadow tree instead of the flat tree. Closes #7207.
* Make it work with the unfocusing steps symmetrically to the focusing steps. Closes #7070.

source

@@ -75042,9 +75042,10 @@ END:VCARD</pre>
 
    <dd>
     <ol>
-     <li><p>If <var>focus target</var> is a <span>shadow-including inclusive ancestor</span> of the
-     <span>currently focused area of a top-level browsing context</span>'s <span>DOM anchor</span>,
-     then return null.</p></li>
+     <li><p>If <var>focus target</var>'s <span data-x="concept-element-shadow-root">shadow
+     root</span> is a <span>shadow-including inclusive ancestor</span> of the <span>currently
+     focused area of a top-level browsing context</span>'s <span>DOM anchor</span>, then return
+     null.</p></li>
 
      <li><p>Let <var>autofocus delegate</var> be the <span>autofocus delegate</span> for <var>focus
      target</var> given <var>focus trigger</var>.</p></li>
@@ -75053,17 +75054,19 @@ END:VCARD</pre>
      delegate</var>.</p></li>
 
      <li><p>If <var>focus trigger</var> is "<code data-x="">click</code>", then let <var>possible
-     focus delegates</var> be the list of all <span>click focusable</span> <span
-     data-x="focusable area">focusable areas</span> whose <span>DOM anchor</span> is a descendant
-     of <var>focus target</var> in the <span>flat tree</span>.</p></li>
+     focus delegates</var> be the list of all <span>click focusable</span> <span data-x="focusable
+     area">focusable areas</span> whose <span>DOM anchor</span> is a <span>shadow-including
+     descendant</span> of <var>focus target</var>'s <span
+     data-x="concept-element-shadow-root">shadow root</span>.</p></li>
 
      <li><p>Otherwise, let <var>possible focus delegates</var> be the list of all <span
-     data-x="focusable area">focusable areas</span> whose <span>DOM anchor</span> is a descendant
-     of <var>focus target</var> in the <span>flat tree</span>.</p></li>
+     data-x="focusable area">focusable areas</span> whose <span>DOM anchor</span> is a
+     <span>shadow-including descendant</span> of <var>focus target</var>'s <span
+     data-x="concept-element-shadow-root">shadow root</span>.</p></li>
 
-     <li><p>Return the first <span>focusable area</span> in <span>tree order</span> of who their
-     <span data-x="DOM anchor">DOM anchors</span> are in <var>possible focus delegates</var>, or
-     null if <var>possible focus delegates</var> is empty.</p></li>
+     <li><p>Return the first <span>focusable area</span> in <span>shadow-including tree
+     order</span> of who their <span data-x="DOM anchor">DOM anchors</span> are in <var>possible
+     focus delegates</var>, or null if <var>possible focus delegates</var> is empty.</p></li>
     </ol>
 
     <p class="note">For <span data-x="sequentially focusable">sequential focusability</span>, the
@@ -75166,6 +75169,14 @@ END:VCARD</pre>
    <!-- https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=2819 -->
    <!-- https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=2822 -->
 
+   <li><p>If <var>old focus target</var> is a <span>shadow host</span> whose <span
+   data-x="concept-element-shadow-root">shadow root</span>'s <span>delegates focus</span> is true,
+   and <var>old focus target</var>'s <span data-x="concept-element-shadow-root">shadow root</span>
+   is a <span>shadow-including inclusive ancestor</span> of the <span>currently focused area of a
+   top-level browsing context</span>'s <span>DOM anchor</span>, then set <var>old focus
+   target</var> to that <span>currently focused area of a top-level browsing
+   context</span>.</p></li>
+
    <li><p>If <var>old focus target</var> is <span>inert</span>, then return.</p></li>
 
    <li>