Guard showModal() and showPopover() with fully active checks

Closes #10659. This effectively only impacts dialogs and popovers "synthetic" documents, such as those created via document.implementation.createHTMLDocument().

source

@@ -61772,6 +61772,9 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    <li><p>If <span>this</span> has an <code data-x="attr-dialog-open">open</code> attribute, then
    throw an <span>"<code>InvalidStateError</code>"</span> <code>DOMException</code>.</p></li>
 
+   <li><p>If <span>this</span>'s <span>node document</span> is not <span>fully active</span>, then
+   throw an <span>"<code>InvalidStateError</code>"</span> <code>DOMException</code>.</p></li>
+
    <li><p>If <span>this</span> is not <span>connected</span>, then throw an
    <span>"<code>InvalidStateError</code>"</span> <code>DOMException</code>.</p></li>
 
@@ -61801,9 +61804,8 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    to the top layer</span> given <span>this</span>.</p></li>
 
    <li id="canceling-dialogs">
-    <p>If <span>this</span>'s <span>node document</span> is <span>fully active</span>, then set
-    <span>this</span>'s <span data-x="dialog-close-watcher">close watcher</span> to the result of
-    <span data-x="establish a close watcher">establishing a close watcher</span> given
+    <p>Set <span>this</span>'s <span data-x="dialog-close-watcher">close watcher</span> to the
+    result of <span data-x="establish a close watcher">establishing a close watcher</span> given
     <span>this</span>'s <span>relevant global object</span>, with:</p>
 
     <ul>
@@ -61817,10 +61819,6 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
      <li><p><i data-x="create-close-watcher-closeAction">closeAction</i> being to <span>close the
      dialog</span> given <span>this</span> and null.</p></li>
     </ul>
-
-    <p class="XXX">It would be better if this method failed early for the non-<span>fully
-    active</span> case. That is being tracked in <a
-    href="https://github.com/whatwg/html/issues/10659">issue #10659</a>.</p>
    </li>
 
    <li><p>Set <span>this</span>'s <span>previously focused element</span> to the
@@ -85549,10 +85547,9 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
      </li>
 
      <li id="canceling-popovers">
-      <p>If <var>document</var> is <span>fully active</span>, then set <var>element</var>'s
-      <span>popover close watcher</span> to the result of <span data-x="establish a close
-      watcher">establishing a close watcher</span> given <var>element</var>'s <span>relevant global
-      object</span>, with:</p>
+      <p>Set <var>element</var>'s <span>popover close watcher</span> to the result of <span
+      data-x="establish a close watcher">establishing a close watcher</span> given
+      <var>element</var>'s <span>relevant global object</span>, with:</p>
 
       <ul>
        <li><p><i data-x="create-close-watcher-cancelAction">cancelAction</i> being to return
@@ -85562,10 +85559,6 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
        data-x="hide popover algorithm">hide a popover</span> given <var>element</var>, true, true,
        and false.</p></li>
       </ul>
-
-      <p class="XXX">It would be better if this algorithm failed early for the non-<span>fully
-      active</span> case. That is being tracked in <a
-      href="https://github.com/whatwg/html/issues/10659">issue #10659</a>.</p>
      </li>
     </ol>
    </li>
@@ -86108,6 +86101,9 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
     <ul>
      <li><p><var>element</var> is not <span>connected</span>;</p></li>
 
+     <li><p><var>element</var>'s <span>node document</span> is not <span>fully
+     active</span>;</p></li>
+
      <li><p><var>expectedDocument</var> is not null and <var>element</var>'s <span>node
      document</span> is not <var>expectedDocument</var>;</p></li>