[w3c/webauthn] c9b20a: Fix interface/member confusion

  Branch: refs/heads/vgb-u2f-attestation
  Home:   https://github.com/w3c/webauthn
  Commit: c9b20a595e14fcc45a45e8ffca2c4a7632087820
      https://github.com/w3c/webauthn/commit/c9b20a595e14fcc45a45e8ffca2c4a7632087820
  Author: Vijay Bharadwaj <vijaybh@users.noreply.github.com>
  Date:   2017-02-08 (Wed, 08 Feb 2017)

  Changed paths:
    M index.bs

  Log Message:
  -----------
  Fix interface/member confusion

Thanks to @equalsJeffH for spotting this.