Note: this enums are not a part of the public API.

Prior to this commit, the compiler produced:

```js
var DateType;
(function (DateType) {
    DateType[DateType["FullYear"] = 0] = "FullYear";
    DateType[DateType["Month"] = 1] = "Month";
    DateType[DateType["Date"] = 2] = "Date";
    DateType[DateType["Hours"] = 3] = "Hours";
    DateType[DateType["Minutes"] = 4] = "Minutes";
    DateType[DateType["Seconds"] = 5] = "Seconds";
    DateType[DateType["FractionalSeconds"] = 6] = "FractionalSeconds";
    DateType[DateType["Day"] = 7] = "Day";
})(DateType || (DateType = {}));
```

With these changes, we allow objects to be dropped entirely and inlined.

PR Close #59468