Features: CST element collection

[forivall]

I have a proof of concept for post processing babylon's ast to add the CST-in-AST nodes specified in https://github.com/estree/estree/pull/107 at https://github.com/forivall/tacoscript/tree/master/packages/cstify.

There's also a much more robust implementation at https://github.com/cst/cst

I'm not sure if this should be in features, or in a separate CST area.

[ariya]

Most likely a separate topic. Features discuss the built-in abilities of a parser.