How to recover public key with ECDSA?

Any suggestions on how to implement [public key recovery](http://crypto.stackexchange.com/questions/18105/how-does-recovering-the-public-key-from-an-ecdsa-signature-work) with WebCrypto ECDSA?

How is (r,s) encoded in the output buffer of `sign`?
Is it just `r = [0,32)` and `s = [32,64)` for `curve = P-256` ([docs](https://www.w3.org/TR/2016/PR-WebCryptoAPI-20161215/#ecdsa-operations)) ?

Seams like [elliptic.js](https://github.com/indutny/elliptic/blob/cbace4683a4a548dc0306ef36756151a20299cd5/lib/elliptic/ec/index.js#L190) implements the recovery and it should be possible to import the recovered public key via jwk back into WebCrypto ...