Add Drupal.truncateUtf8

(I thought I submitted this just now, but it's not showing up.)

Drupal.truncateUtf8 = function (string, len, wordsafe, dots) {
  if (string.length <= len) {
    return string;
  }

  if (dots) {
    len -= 4;
  }

  if (wordsafe) {
    string = string.substring(0, len + 1);
    if (lastSpace = string.lastIndexOf(' ')) {
      string = string.substring(0, lastSpace);
    }
    else {
      string = string.substring(0, len);
    }
  }
  else {
    string = string.substring(0, len);
  }

  if (dots) {
    string += ' ...';
  }

  return string;
}