Allow null candidate in RTCPeerConnection.addIceCandidate (microsoft#1739)

Co-authored-by: saschanaz <[email protected]>

Author: silverlyra

Diff for: baselines/dom.generated.d.ts

@@ -18158,9 +18158,9 @@ interface RTCPeerConnection extends EventTarget {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/RTCPeerConnection/signalingState) */
     readonly signalingState: RTCSignalingState;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/RTCPeerConnection/addIceCandidate) */
-    addIceCandidate(candidate?: RTCIceCandidateInit): Promise<void>;
+    addIceCandidate(candidate?: RTCIceCandidateInit | null): Promise<void>;
     /** @deprecated */
-    addIceCandidate(candidate: RTCIceCandidateInit, successCallback: VoidFunction, failureCallback: RTCPeerConnectionErrorCallback): Promise<void>;
+    addIceCandidate(candidate: RTCIceCandidateInit | null, successCallback: VoidFunction, failureCallback: RTCPeerConnectionErrorCallback): Promise<void>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/RTCPeerConnection/addTrack) */
     addTrack(track: MediaStreamTrack, ...streams: MediaStream[]): RTCRtpSender;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/RTCPeerConnection/addTransceiver) */

Diff for: inputfiles/overridingTypes.jsonc

@@ -2169,7 +2169,21 @@
                     "method": {
                         "addIceCandidate": {
                             "signature": {
+                                "0": {
+                                    "param": [
+                                        {
+                                            "name": "candidate",
+                                            "nullable": true
+                                        }
+                                    ]
+                                },
                                 "1": {
+                                    "param": [
+                                        {
+                                            "name": "candidate",
+                                            "nullable": true
+                                        }
+                                    ],
                                     "deprecated": true
                                 }
                             }