function domTestClass(node, className) {
  var cn = domClassName(node).split(/\s+/);
  for (var i = 0; i < jsLength(cn); ++i) {
    if (cn[i] == className) {
      return true;
    }
  }
  return false;
}
Checks if a node belongs to a style class.

@param {Element} node  DOM element to test.
@param {String} className  Class name to check for.
@return {Boolean}  Node belongs to style class.