Add serializers to RTCIceCandidate and RTCSessionDescription

Source/modules/mediastream/RTCSessionDescription.cpp

Index: Source/modules/mediastream/RTCSessionDescription.cpp
diff --git a/Source/modules/mediastream/RTCSessionDescription.cpp b/Source/modules/mediastream/RTCSessionDescription.cpp
index 9ec76397308f91115c683ab25dd932275ab1b109..60db5834b2ef203bd7b5ca52a646fb6c06077304 100644
--- a/Source/modules/mediastream/RTCSessionDescription.cpp
+++ b/Source/modules/mediastream/RTCSessionDescription.cpp
@@ -31,6 +31,8 @@
 #include "config.h"
 #include "modules/mediastream/RTCSessionDescription.h"
 
+#include "bindings/core/v8/ScriptValue.h"
+#include "bindings/core/v8/V8ObjectBuilder.h"
 #include "modules/mediastream/RTCSessionDescriptionInit.h"
 
 namespace blink {
@@ -78,6 +80,20 @@ void RTCSessionDescription::setSdp(const String& sdp)
     m_webSessionDescription.setSDP(sdp);
 }
 
+ScriptValue RTCSessionDescription::toJSONForBinding(ScriptState* scriptState)
+{
+    V8ObjectBuilder result(scriptState);
+    if (type().isNull())
+        result.addNull("type");
+    else
+        result.addString("type", type());
+    if (sdp().isNull())
+        result.addNull("sdp");
+    else
+        result.addString("sdp", sdp());
+    return result.scriptValue();
+}
+
 WebRTCSessionDescription RTCSessionDescription::webSessionDescription()
 {
     return m_webSessionDescription;