title: ::before/::after + flexbox in MDN
body: <p>I see the following news item on <a href="https://developer.mozilla.org/en-US/docs/Web/CSS">MDN CSS</a> homepage:</p>
  
  <blockquote>
    <p>Gecko's support of flexible boxes has been adapted to match a recent specification clarification: from Firefox 23 <code>::before</code> and <code>::after</code> will be flex items, and as such can be repositioned using <code>order</code> and <code>align-self</code>.<br>
    (May 3rd, 2013)</p>
  </blockquote>
  
  <p>What specification does it refer to?<br>
  I cannot find any references to <code>::before</code>/<code>::after</code> in <a href="http://www.w3.org/TR/2012/CR-css3-flexbox-20120918/">CSS Flexible Box Layout Module</a>.</p>