It looks like enumerations have changed in the March CTP of Atlas. To create an enumeration, you now call the Type.createEnum() method like below. In this example, the EnumGBI is created.
Type.createEnum("EnumGBI", "Good", 0, "Bad", 1, "Indifferent", 2); for (var strItems in EnumGBI.getValues()) { strOut += strItems + strReturn; }