Add serializers to RTCIceCandidate and RTCSessionDescription

Source/modules/mediastream/RTCIceCandidate.h

Index: Source/modules/mediastream/RTCIceCandidate.h
diff --git a/Source/modules/mediastream/RTCIceCandidate.h b/Source/modules/mediastream/RTCIceCandidate.h
index d673838d09a1ef04eaf51db21ced05d281cd2b70..e1229b5e10d8b4dfdd482fcdb9e8a67e1bd49eca 100644
--- a/Source/modules/mediastream/RTCIceCandidate.h
+++ b/Source/modules/mediastream/RTCIceCandidate.h
@@ -39,6 +39,8 @@ namespace blink {
 
 class RTCIceCandidateInit;
 class ExceptionState;
+class ScriptState;
+class ScriptValue;
 
 class RTCIceCandidate final : public GarbageCollectedFinalized<RTCIceCandidate>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
@@ -53,6 +55,8 @@ public:
     unsigned short sdpMLineIndex() const;
     void setSdpMLineIndex(unsigned short);
 
+    ScriptValue toJSONForBinding(ScriptState*);
+
     WebRTCICECandidate webCandidate() const;
 
     DEFINE_INLINE_TRACE() { }