add blank space after ex2.html

Author: davidsgrogan

ex2.html

@@ -319,6 +319,9 @@ <h3 id="complex-broken">Example 4: Broken File menu</h3>
   </section>
 </section>
 
+<hr style="margin-bottom: 250px;">
+<!-- Blank space because of https://crbug.com/546207253 -->
+
 <script>
   const supported = "HTMLMenuListElement" in window;
   if (!supported) {