Update fullscreen.bs

Author: foolip

fullscreen.bs

@@ -267,7 +267,7 @@ are:
   </ul>
 
  <li><p>If <var>error</var> is false, then <a>consume user activation</a> given
- <var>pendingDoc</var>'s <a>node navigable</a>'s <a>active window</a>.
+ <var>pendingDoc</var>'s <a>node navigable</a>'s <a for=navigable>active window</a>.
 
  <li><p>Return <var>promise</var>, and run the remaining steps <a>in parallel</a>.