docs: public static void loadClass(Context cx, Scriptable thisObj,
                                   Object[] args, Function funObj)
          throws IllegalAccessException, InstantiationException
      {
          Class<?> clazz = getClass(args);
          if (!Script.class.isAssignableFrom(clazz)) {
              throw reportRuntimeError("msg.must.implement.Script");
          }
          Script script = (Script) clazz.newInstance();
          script.exec(cx, thisObj);
      }