Support of Grouping items in select elements

It should be possible to group items in a select element.

<select name="pets">
  <optgroup label="4-legged pets">
    <option value="dog">Dog</option>
    <option value="cat">Cat</option>
    <option value="hamster" disabled>Hamster</option>
  </optgroup>
  <optgroup label="Flying pets">
    <option value="parrot">Parrot</option>
    <option value="macaw">Macaw</option>
    <option value="albatross">Albatross</option>
  </optgroup>
</select>

Links / references

• W3C - The select element: https://www.w3.org/TR/html50/forms.html#the-select-element
• MDN - The optgroup element: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/optgroup