multiline object type aliases

I really want to write this:

```
type Whatever = {
  field1: Type1
  field2: Type2
  field3: Type3
  ...
  // 10 or so more fields
}
```

Happy to put commas in there if I must or put newlines in different places.

From the grammar, examples, and my experimentation, I cannot sort out how to format such a thing in a sane manner. How should I proceed?

It seems straightforward enough to modify the grammar, but I wonder if things are the way they are for a good reason.