dont allow parent select for default submit button

Author: josepharhar

source

@@ -60372,7 +60372,8 @@ fur
 
   <p>A <code>form</code> element's <dfn>default button</dfn> is the first <span
   data-x="concept-submit-button">submit button</span> in <span>tree order</span> whose <span>form
-  owner</span> is that <code>form</code> element.</p>
+  owner</span> is that <code>form</code> element and whose <span>parent</span> node is not a
+  <code>select</code> element.</p>
 
   <p>If the user agent supports letting the user submit a form implicitly (for example, on some
   platforms hitting the "enter" key while a text control is <span>focused</span> implicitly submits