How to detect the support of streams

[martinheidegger]

Reading the explainer I am wondering how to detect it once the API is supported. In a preceding comment it is mentioned that try/catch could suffice to detect support, however in a simple API test I noticed that during sign(algorithm, key, data) will throw a TypeError both with a wrong key or a wrong data object. It seems like a support property could come in handy? Something like crypto.subtle.supportsStreams?