Bug 1620448: Have addIceCandidate's chained steps return rejected promise when remoteDescription is null. r=bwc

Differential Revision: https://phabricator.services.mozilla.com/D65637

--HG--
extra : moz-landing-system : lando

dom/media/PeerConnection.jsm

@@ -1294,7 +1294,16 @@ class RTCPeerConnection {
     usernameFragment,
   }) {
     this._checkClosed();
-    return this._chain(() => {
+    return this._chain(async () => {
+      if (
+        !this._impl.pendingRemoteDescription.length &&
+        !this._impl.currentRemoteDescription.length
+      ) {
+        throw new this._win.DOMException(
+          "No remoteDescription.",
+          "InvalidStateError"
+        );
+      }
       return new Promise((resolve, reject) => {
         this._onAddIceCandidateSuccess = resolve;
         this._onAddIceCandidateError = reject;

testing/web-platform/meta/webrtc/RTCPeerConnection-operations.https.html.ini

@@ -1,8 +1,4 @@
 [RTCPeerConnection-operations.https.html]
-  [addIceCandidate must detect InvalidStateError synchronously when chain is empty]
-    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1620448
-    expected: FAIL
-
   [sender.getStats does NOT use the operations chain]
     bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1620689
     expected: FAIL