getIdentifierKind method
Implementation
@override
int getIdentifierKind() {
  // Is the identifier a unit type?
  var tokId = -1;
  if (tokId == -1) {
    tokId = (_text.substring(_startIndex, _index) == '!important') ? TokenKind.IMPORTANT : -1;
  }
  return tokId >= 0 ? tokId : TokenKind.IDENTIFIER;
}