Update IDL to 1847

modules/mediastream/RTCPeerConnection.idl

Index: modules/mediastream/RTCPeerConnection.idl
diff --git a/modules/mediastream/RTCPeerConnection.idl b/modules/mediastream/RTCPeerConnection.idl
index 1be4b2400903464fe585023671da9e909638bfa6..0cd960892be46a97674d2f10b2d4680abd8a816b 100644
--- a/modules/mediastream/RTCPeerConnection.idl
+++ b/modules/mediastream/RTCPeerConnection.idl
@@ -61,8 +61,8 @@
     sequence<MediaStream> getRemoteStreams();
     MediaStream getStreamById(DOMString streamId);
 
-    [StrictTypeChecking, RaisesException] void addStream(MediaStream stream, optional Dictionary mediaConstraints);
-    [StrictTypeChecking, RaisesException] void removeStream(MediaStream stream);
+    [StrictTypeChecking, RaisesException] void addStream(MediaStream? stream, optional Dictionary mediaConstraints);
+    [StrictTypeChecking, RaisesException] void removeStream(MediaStream? stream);
 
     void getStats(RTCStatsCallback successCallback, [Default=Undefined] optional MediaStreamTrack selector);
 
@@ -80,4 +80,3 @@
     attribute EventHandler oniceconnectionstatechange;
     attribute EventHandler ondatachannel;
 };
-