Improve comment block annotation parsing

[c9s]

@font-face {
  font-family: MyGentium;
  src: local(Gentium Bold),    /* should ignore */
       local(Gentium-Bold),    /* should ignore */
       url(GentiumBold.woff);  /* annotation of this declaration */
  font-weight: bold;
}

@font-face {
  /* annotation of the font-family declaration */
  font-family: MyGentium;
  font-weight: bold;
}

  /* annotation of the font-face statement */
@font-face {
  font-family: MyGentium;
  font-weight: bold;
}