function hideSuitesWithout (classname) {
  var suites = document.getElementsByClassName('suite');
  for (var i = 0; i < suites.length; i++) {
    var els = suites[i].getElementsByClassName(classname);
    if (!els.length) {
      suites[i].className += ' hidden';
    }
  }
}
Check for suites that do not have elements
with `classname`, and hide them.

@param {text} classname