Fix regression in focus chain computation

This regressed in 90a60b2, which
accidentally removed the step which lets the recursion continue by
setting the current object to the appropriate "owner" document. Even
though control group owner objects are removed, we still need to
traverse up to the document in focus chain computation.

While here, this rewrites the algorithm to use a loop instead of a goto
for clarity.

Closes #6161.

Author: domenic

source

@@ -72719,33 +72719,48 @@ END:VCARD</pre>
   list constructed as follows:</p>
 
   <ol>
-   <li><p>Let <var>current object</var> be <var>subject</var>.</p></li>
+   <li><p>Let <var>output</var> be an empty <span>list</span>.</p></li>
 
-   <li><p>Let <var>output</var> be an empty list.</p></li>
-
-   <li><p><i>Loop</i>: Append <var>current object</var> to <var>output</var>.</p></li>
+   <li><p>Let <var>currentObject</var> be <var>subject</var>.</p></li>
 
    <li>
-    <p>If <var>current object</var> is an <code>area</code> element's shape, append
-    that <code>area</code> element to <var>output</var>.</p>
+    <p>While true:</p>
 
-    <p>Otherwise, if <var>current object</var> is a <span>focusable area</span> whose <span>DOM
-    anchor</span> is an element that is not <var>current object</var> itself, append that
-    <span>DOM anchor</span> element to <var>output</var>.</p>
-   </li>
+    <ol>
+     <li><p><span data-x="list append">Append</span> <var>currentObject</var> to
+     <var>output</var>.</p></li>
 
-   <li><p>If <var>current object</var> is a <code>Document</code> whose <span
-   data-x="concept-document-bc">browsing context</span> is a <span>child browsing context</span>,
-   then set <var>current object</var> to <var>current object</var>'s <span
-   data-x="concept-document-bc">browsing context</span>'s <span
-   data-x="bc-container">container</span> and return to the step labeled <i>loop</i>.</p></li>
+     <li>
+      <p>If <var>currentObject</var> is an <code>area</code> element's shape, then <span
+      data-x="list append">append</span> that <code>area</code> element to <var>output</var>.</p>
+
+      <p>Otherwise, if <var>currentObject</var>'s <span>DOM anchor</span> is an element that is not
+      <var>currentObject</var> itself, then <span data-x="list append">append</span>
+      <var>currentObject</var>'s <span>DOM anchor</span> to <var>output</var>.</p>
+     </li>
+
+     <li>
+      <p>If <var>currentObject</var> is a <span>focusable area</span>, then set
+      <var>currentObject</var> to <var>currentObject</var>'s <span>DOM anchor</span>'s <span>node
+      document</span>.</p>
+
+      <p>Otherwise, if <var>currentObject</var> is a <code>Document</code> whose <span
+      data-x="concept-document-bc">browsing context</span> is a <span>child browsing context</span>,
+      then set <var>currentObject</var> to <var>currentObject</var>'s <span
+      data-x="concept-document-bc">browsing context</span>'s <span
+      data-x="bc-container">container</span>.</p>
+
+      <p>Otherwise, <span>break</span>.</p>
+     </li>
+    </ol>
+   </li>
 
    <li>
     <p>Return <var>output</var>.</p>
 
-    <p class="note">The chain starts with <var>subject</var> and (if <var>subject</var> is or can be the <span>currently focused area of a top-level browsing
-    context</span>) continues up the focus hierarchy up to the <code>Document</code> of the
-    <span>top-level browsing context</span>.</p>
+    <p class="note">The chain starts with <var>subject</var> and (if <var>subject</var> is or can be
+    the <span>currently focused area of a top-level browsing context</span>) continues up the focus
+    hierarchy up to the <code>Document</code> of the <span>top-level browsing context</span>.</p>
    </li>
   </ol>