Browser extension WebAuthn PRF extension not spec-compliant

Hi there,

Noticed that the 1Password browser extension returns a non-spec-compliant response type when trying to create a credential with the WebAuthn PRF extension.

I came across this while building a project using https://github.com/FiloSottile/typage#encrypt-and-decrypt-a-file-with-a-passkey.

According to https://w3c.github.io/webauthn/#dictdef-authenticationextensionsprfvalues, the `results` should be of type https://webidl.spec.whatwg.org/#BufferSource which is an `ArrayBuffer` or an `ArrayBufferView`. In poking around in my browser, it seems the 1Password implementation returns a plain `Array`.

I've got a fix ready for that specific library (I've contacted the author to see if they'd accept a PR) but figured I'd mention it to you folks as well just in case.