binding: Lets Dictionary::getPropertyNames, etc. rethrow an exception.

third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl

Index: third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl
diff --git a/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl b/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl
index 2e48d3ee8ebb1883df9c06a7b7a5a0cc86617bbb..de9f6a4b3357ac93893427a75f9f05d4838da2e5 100644
--- a/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl
+++ b/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.idl
@@ -95,7 +95,7 @@ enum RTCIceConnectionState {
 
     // https://w3c.github.io/webrtc-pc/#legacy-interface-extensions
     // These methods return Promise<void> because having Promise-based versions requires that all overloads return Promises.
-    [CallWith=ScriptState] Promise<void> createOffer(RTCSessionDescriptionCallback successCallback, RTCPeerConnectionErrorCallback failureCallback, optional Dictionary rtcOfferOptions);
+    [CallWith=ScriptState, RaisesException] Promise<void> createOffer(RTCSessionDescriptionCallback successCallback, RTCPeerConnectionErrorCallback failureCallback, optional Dictionary rtcOfferOptions);
     // TODO(guidou): There should be no mediaConstraints argument.
     [CallWith=ScriptState] Promise<void> createAnswer(RTCSessionDescriptionCallback successCallback, RTCPeerConnectionErrorCallback failureCallback, optional Dictionary mediaConstraints);
     [CallWith=ScriptState] Promise<void> setLocalDescription(RTCSessionDescriptionInit description, VoidCallback successCallback, [Default=Undefined] optional RTCPeerConnectionErrorCallback failureCallback);