Constant from extension method?

Any way something like this could work?

```dart
extension Time on int {
Duration get ms =>
Duration(microseconds: (this * Duration.microsecondsPerMillisecond).toInt());
}

main() {
// const time = Duration(milliseconds: 250);
const time = 250.ms;
print(time);
}
```

as long as `this` is itself `const`?