third_party/blink/manual_tests/select-scroll.html

<p>
When you click the following &lt;select&gt;, you should see a scrollbar,
and should be able to scroll down to see "Z" as the last option.
See <a href="https://bugs.webkit.org/show_bug.cgi?id=49306">Bug 49306</a> for detail.

<p>
<select>
 <option>A</option>
 <option>B</option>
 <option>C</option>
 <option>D</option>
 <option>E</option>
 <option>F</option>
 <option>G</option>
 <option>H</option>
 <option>I</option>
 <option>J</option>
 <option>K</option>
 <option>L</option>
 <option>M</option>
 <option>N</option>
 <option>O</option>
 <option>P</option>
 <option>Q</option>
 <option>R</option>
 <option>S</option>
 <option>T</option>
 <option>U</option>
 <option>V</option>
 <option>W</option>
 <option>X</option>
 <option>Y</option>
 <option>Z</option>
</select>