Make auto popover list an algorithm

Fixes whatwg#9036

This patch also fixes a call to topmost auto popover which was passing
an element instead of a document.

source

@@ -82002,11 +82002,6 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
    data-x="popover-showing-state">showing</dfn></p></li>
   </ul>
 
-  <p>The <code>Document</code> has an <dfn>auto popover list</dfn>, which is a <span>list</span> of
-  all the elements in the <code>Document</code>'s <span>top layer</span> whose <code
-  data-x="attr-popover">popover</code> attribute is in the <span
-  data-x="attr-popover-auto-state">auto</span> state, in the same order.</p>
-
   <p>The <code>Document</code> has a <dfn>popover pointerdown target</dfn>, which is an <span
   data-x="HTML elements">HTML element</span> or null, initially null.</p>
 
@@ -82581,6 +82576,25 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
    <li><p>Return true.</p></li>
   </ol>
 
+  <p>To get the <dfn>auto popover list</dfn> for a <code>Document</code> <var>document</var>:</p>
+
+  <ol>
+   <li><p>Let <var>popovers</var> be an empty <span>list</span>.</p></li>
+
+   <li>
+    <p>For each <code>Element</code> <var>element</var> in <var>document</var>'s <span>top
+    layer</span>:</p>
+
+    <ol>
+     <li><p>If <var>element</var>'s <span>popover visibility state</span> is <span
+     data-x="popover-showing-state">showing</span>, then <span data-x="list append">append</span>
+     <var>element</var> to <var>popovers</var>.</p></li>
+    </ol>
+   </li>
+
+   <li><p>Return <var>popovers</var>.</p></li>
+  </ol>
+
   <h4>The popover target attributes</h4>
 
   <p><span data-x="concept-button">Buttons</span> may have the following content attributes:</p>
@@ -82757,13 +82771,13 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
    <li><p>Let <var>target</var> be <var>event</var>'s <span
    data-x="concept-event-target">target</span>.</p></li>
 
+   <li><p>Let <var>document</var> be <var>target</var>'s <span>node document</span>.</p></li>
+
    <li><p>Let <var>topmostPopover</var> be the result of running <span>topmost auto popover</span>
-   given <var>target</var>.</p></li>
+   given <var>document</var>.</p></li>
 
    <li><p>If <var>topmostPopover</var> is null, then return.</p></li>
 
-   <li><p>Let <var>document</var> be <var>target</var>'s <span>node document</span>.</p></li>
-
    <li><p>If <var>event</var> is a <code>PointerEvent</code> and <var>event</var>'s <code
    data-x="dom-Event-type">type</code> is <code data-x="event-pointerdown">pointerdown</code>, then:
    set <var>document</var>'s <span>popover pointerdown target</span> to the result of running