Problem on dealing with 'unicode-range' in '@font-face' at-rule

https://developer.mozilla.org/en-US/docs/Web/CSS/unicode-range
This is an experimental technology supported by Webkit and useful in Stylebot that using this parser.
jscssp prases this

@font-face {
  font-family: 'Ampersand';
  src: local('Times New Roman');
  unicode-range: U+26;
}

into

@font-face {

  font-family: 'Ampersand';
  src: local('Times New Roman');

  unicode-range: U +26;
}

and just makes unicode-range not working...