Introduce FocusOptions.focusVisible.

Fixes whatwg#7830

source

@@ -77469,6 +77469,7 @@ 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 +77630,12 @@ 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 <code data-x="">true</code>,
+   or is not present but matches an <span>implementation-defined</span> heuristic,
+   then <a href="https://drafts.csswg.org/selectors/#indicate-focus">indicate focus</a>.</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