Make RemoveSnapshotsInSyncListener run on the async queue. (#5632)
Make RemoveSnapshotsInSyncListener run on the async queue. (#5632)


firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk