dom: Add WebRTC transceiver stubs.

components/script/dom/webidls/RTCRtpTransceiver.webidl

@@ -0,0 +1,24 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://w3c.github.io/webrtc-pc/#rtcrtptransceiver-interface
+
+[Exposed=Window, Pref="dom.webrtc.transceiver.enabled"]
+interface RTCRtpTransceiver {
+  //readonly attribute DOMString? mid;
+  [SameObject] readonly attribute RTCRtpSender sender;
+  //[SameObject] readonly attribute RTCRtpReceiver receiver;
+  attribute RTCRtpTransceiverDirection direction;
+  //readonly attribute RTCRtpTransceiverDirection? currentDirection;
+  //void stop();
+  //void setCodecPreferences(sequence<RTCRtpCodecCapability> codecs);
+};
+
+enum RTCRtpTransceiverDirection {
+  "sendrecv",
+  "sendonly",
+  "recvonly",
+  "inactive",
+  "stopped"
+};