[webauthn] Merged Pull Request: Correct Android Key attestation verification procedure

equalsJeffH has just merged arnar's pull request 717 for https://github.com/w3c/webauthn:

== Correct Android Key attestation verification procedure ==
Fixes #599


<!--
    This comment and the below content is programatically generated.
    You may add a comma-separated list of anchors you'd like a
    direct link to below (e.g. #idl-serializers, #idl-sequence):

    Don't remove this comment or modify anything below this line.
    If you don't want a preview generated for this pull request,
    just replace the whole of this comment's content by "no preview"
    and remove what's below.
-->
***
<a href="https://pr-preview.s3.amazonaws.com/arnar/webauthn/pull/717.html" title="Last updated on Dec 8, 2017, 12:59 AM GMT (10796c0)">Preview</a> | <a href="https://pr-preview.s3.amazonaws.com/w3c/webauthn/717/33ac796...arnar:10796c0.html" title="Last updated on Dec 8, 2017, 12:59 AM GMT (10796c0)">Diff</a>

See https://github.com/w3c/webauthn/pull/717