--- a/testing/web-platform/tests/interfaces/webrtc.idl
+++ b/testing/web-platform/tests/interfaces/webrtc.idl
@@ -292,16 +292,17 @@ dictionary RTCRtpParameters {
              required RTCRtcpParameters rtcp;
              required sequence<RTCRtpCodecParameters> codecs;
 };
 
 dictionary RTCRtpSendParameters : RTCRtpParameters {
              required DOMString transactionId;
              required sequence<RTCRtpEncodingParameters> encodings;
              RTCDegradationPreference degradationPreference = "balanced";
+             RTCPriorityType priority = "low";
 };
 
 dictionary RTCRtpReceiveParameters : RTCRtpParameters {
              required sequence<RTCRtpDecodingParameters> encodings;
 };
 
 dictionary RTCRtpCodingParameters {
              DOMString rid;
@@ -309,17 +310,16 @@ dictionary RTCRtpCodingParameters {
 
 dictionary RTCRtpDecodingParameters : RTCRtpCodingParameters {
 };
 
 dictionary RTCRtpEncodingParameters : RTCRtpCodingParameters {
              octet codecPayloadType;
              RTCDtxStatus dtx;
              boolean active = true;
-             RTCPriorityType priority = "low";
              unsigned long ptime;
              unsigned long maxBitrate;
              double maxFramerate;
              double scaleResolutionDownBy;
 };
 
 enum RTCDtxStatus {
          "disabled",