BREAKING CHANGE: This moves documentation.js to Babel 7. From now on,
documentation.js will only support Babel 7: please stick to older
releases if you need to support Babel 6. Additionally, this work
temporarily disables support for following dynamic imports.
* build: Use Flow syntax without comments.
We're switching to Flow annotations - not Flow comments. This
gives documentation.js the ability to self-document without
JSDoc types and improves our compatibility with tools like
prettier.
Fixes#729. Fixes#709
