[webrtc-stats] issuerCertificateId is not described

fippo has just created a new issue for 
https://github.com/w3c/webrtc-stats:

== issuerCertificateId is not described ==
https://w3c.github.io/webrtc-stats/#dom-rtccertificatestats-issuercertificateid
 does not have a description. I assume that it is a pointer to the 
RTCCertificateStats of the certificate next in the chain.
How can I recognize the root here? Missing issuercertificateid (which 
might be pretty common for self-signed certificates) 

Please view or discuss this issue at 
https://github.com/w3c/webrtc-stats/issues/100 using your GitHub 
account