Introduce FocusOptions.focusVisible.

Fixes whatwg#7830

source

@@ -3867,6 +3867,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn
      data-x-href="https://drafts.csswg.org/selectors/#the-focus-visible-pseudo"><code>:focus-visible</code></dfn>
      pseudo-class</li>
+     <li><dfn data-x-href="https://drafts.csswg.org/selectors/#indicate-focus">indicate focus</dfn></li>
     </ul>
 
     <p>The following features are defined in <cite>CSS Values and Units</cite>: <ref
@@ -77469,6 +77470,7 @@ END:VCARD</pre>
 
   <pre><code class="idl">dictionary <dfn dictionary>FocusOptions</dfn> {
   boolean <span data-x="dom-focusoptions-preventscroll">preventScroll</span> = false;
+  boolean <span data-x="dom-focusoptions-focusvisible">focusVisible</span>;
 };</code></pre>
 
   <dl class="domintro">
@@ -77629,6 +77631,12 @@ END:VCARD</pre>
 
    <li><p>Run the <span>focusing steps</span> for the element.</p></li>
 
+   <li><p>If the value of the <dfn dict-member for="FocusOptions"><code
+   data-x="dom-focusoptions-focusvisible">focusVisible</code></dfn> dictionary member of
+   <var>options</var> is true,
+   or is not present but matches an <span>implementation-defined</span> heuristic,
+   then <span>indicate focus</span>.</p></li>
+
    <li><p>If the value of the <dfn dict-member for="FocusOptions"><code
    data-x="dom-focusoptions-preventscroll">preventScroll</code></dfn> dictionary member of
    <var>options</var> is false, then <span data-x="scroll an element into view">scroll the element