Add "hide all popovers" algorithm

This was requested for cross referencing instead of "hide all popovers
until" here:
whatwg/fullscreen#204 (comment)

This patch also fixes a bug where a null endpoint is passed to hide all
popovers until, but hide all popovers until assumes endpoint is not null
by looking for endpoint's node document. The bug is fixed by adding a
required document parameter to hide all popovers until.

source

@@ -59600,8 +59600,8 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
   and a boolean <var>isModal</var>, are as follows:</p>
 
   <ol>
-   <li><p>Run <span data-x="hide-all-popovers-until">hide all popovers until</span> given null,
-   false, and false.</p></li>
+   <li><p>Run <span>hide all popovers</span> given <var>subject</var>'s <span>node
+   document</span>.</p></li>
 
    <li><p>Let <var>control</var> be null.</p></li>
 
@@ -81438,7 +81438,8 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
      ancestor</span> algorithm given <var>element</var>.</p></li>
 
      <li><p>Run <span data-x="hide-all-popovers-until">hide all popovers until</span> given
-     <var>ancestor</var>, false, and false.</p></li>
+     <var>ancestor</var>'s <span>node document</span>, <var>ancestor</var>, false, and
+     false.</p></li>
 
      <li>
       <p>If <var>originalType</var> is not equal to the value of <var>element</var>'s <code
@@ -81564,8 +81565,8 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
 
     <ol>
      <li><p>Run <span data-x="hide-all-popovers-until">hide all popovers until</span> given
-     <var>element</var>, <var>focusPreviousElement</var>, and
-     <var>dontFireEvents</var>.</p></li>
+     <var>element</var>'s <span>node document</span>, <var>element</var>,
+     <var>focusPreviousElement</var>, and <var>dontFireEvents</var>.</p></li>
 
      <li>
       <p>If <var>element</var> is not in <var>document</var>'s <span>auto popover list</span>:</p>
@@ -81655,13 +81656,12 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
    given <span>this</span> and true.</p></li>
   </ol>
 
-  <p>To <dfn data-x="hide-all-popovers-until">hide all popovers until</dfn>, given an <span
-  data-x="HTML elements">HTML element</span> <var>endpoint</var>, a boolean
-  <var>focusPreviousElement</var>, and a boolean <var>dontFireEvents</var>:</p>
+  <p>To <dfn data-x="hide-all-popovers-until">hide all popovers until</dfn>, given a
+  <code>Document</code> <var>document</var>, an <span data-x="HTML elements">HTML element</span> or
+  null <var>endpoint</var>, a boolean <var>focusPreviousElement</var>, and a boolean
+  <var>dontFireEvents</var>:</p>
 
   <ol>
-   <li><p>Let <var>document</var> be <var>endpoint</var>'s <span>node document</span>.</p></li>
-
    <li>
     <p>Let <var>closeAllOpenPopovers</var> be an algorithm which performs the following steps:</p>
 
@@ -81723,6 +81723,10 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
   happens. For example, during light-dismiss of a popover, this algorithm ensures that we close only
   the popovers that aren't related to the node clicked by the user.</p>
 
+  <p>To <dfn export>hide all popovers</dfn>, given a <code>Document</code> <var>document</var>, run
+  <span data-x="hide-all-popovers-until">hide all popovers until</span> given <var>document</var>,
+  null, false, and false.</p>
+
   <p>To find the <dfn>topmost popover ancestor</dfn>, given a <code>Node</code>
   <var>newPopover</var>, perform the following steps. They return an <span data-x="HTML
   elements">HTML element</span> or null.</p>
@@ -82121,7 +82125,8 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
      <li><p>Set <var>document</var>'s <span>popover pointerdown target</span> to null.</p></li>
 
      <li><p>If <var>sameTarget</var> is true, then run <span data-x="hide-all-popovers-until">hide
-     all popovers until</span> given <var>ancestor</var>, false, and false.</p></li>
+     all popovers until</span> given <var>ancestor</var>'s <span>node document</span>,
+     <var>ancestor</var>, false, and false.</p></li>
     </ol>
    </li>
   </ol>