Should we allow Flowtype import type statements when sourceType:script?

[loganfsmyth]

We don't currently, but I'm thinking we should?

Flowtype doesn't seem to have a concept of sourceType. It just accepts import statements as normal statements, and doesn't worry about the grammar differences. I don't think we can go that far since Babel needs to follow to ECMA spec for parsing, but we could potentially allow import type {Foo} from ''; statements since import type is Flow-specific. We should double-check this with someone working on Flow ideally, but it seems to be the case from what I can tell.

Not sure is this is a concern for Typescript too.

Important since I'd like to nail down our approach to parsing in babel/babel#6242

[loganfsmyth]

cc @samwgoldman

[loganfsmyth]

@avikchaudhuri Do you happen to know if the Flow team has an opinion on this? My assumption is that Flow doesn't really care whether JS considers a file an ES6 module or a CommonJS module, but it'd be good to get an official confirmation so we don't risk affecting things further in the future.