[BUG] Generated content is unescaped

a:before
{
   content: "<b>bold</b>";
}

validates fine - but the validator generated html produced is:

<b>bold</b>

when it should[1] be:

&lt;b&gt;bold&lt;/b&gt;

- p

--
1. http://www.w3.org/TR/html4/charset.html#didx-character_entity_references