function NativeConnection() {
  MongooseConnection.apply(this, arguments);
  this._listening = false;
  // Tracks the last time (as unix timestamp) the connection received a
  // serverHeartbeatSucceeded or serverHeartbeatFailed event from the underlying MongoClient.
  // If we haven't received one in a while (like due to a frozen AWS Lambda container) then
  // `readyState` is likely stale.
  this._lastHeartbeatAt = null;
}
A [node-mongodb-native](https://github.com/mongodb/node-mongodb-native) connection implementation.

@inherits Connection
@api private