Update interfaces/webrtc-stats.idl (#23138)

Source: https://github.com/tidoust/reffy-reports/blob/6c8209e/ed/idl/webrtc-stats.idl
Build: https://travis-ci.org/tidoust/reffy-reports/builds/677675065
diff --git a/interfaces/webrtc-stats.idl b/interfaces/webrtc-stats.idl
index 65bd922..e3c2da8 100644
--- a/interfaces/webrtc-stats.idl
+++ b/interfaces/webrtc-stats.idl
@@ -189,6 +189,7 @@
 dictionary RTCMediaSourceStats : RTCStats {
              DOMString       trackIdentifier;
              DOMString       kind;
+             boolean         relayedSource;
 };
 
 dictionary RTCAudioSourceStats : RTCMediaSourceStats {
@@ -229,10 +230,8 @@
 
 dictionary RTCMediaHandlerStats : RTCStats {
              DOMString           trackIdentifier;
-             boolean             remoteSource;
              boolean             ended;
              DOMString           kind;
-             RTCPriorityType     priority;
 };
 
 dictionary RTCVideoHandlerStats : RTCMediaHandlerStats {
@@ -274,7 +273,9 @@
              unsigned long long    bytesReceived;
              DOMString             rtcpTransportStatsId;
              RTCIceRole            iceRole;
+             DOMString             iceLocalUsernameFragment;
              RTCDtlsTransportState dtlsState;
+             RTCIceTransportState  iceState;
              DOMString             selectedCandidatePairId;
              DOMString             localCertificateId;
              DOMString             remoteCertificateId;