Function joinClasses

GUI/codemirror/lib/codemirror.js:7134–7139

(a, b)

    if (!classTest(cls).test(node.className)) node.className += " " + cls;
  }
  function joinClasses(a, b) {
    var as = a.split(" ");
    for (var i = 0; i < as.length; i++)
      if (as[i] && !classTest(as[i]).test(b)) b += " " + as[i];
    return b;
  }

  // FEATURE DETECTION