title: firebase onDisconnect() is not fired when user lose connection
body: <p>Hello React native community, I'm trying to use <code>onDisconnect()</code> in <code>firebase</code> but the problem is that the void isn't getting fired when the network loses its connection but it is working if I close the app or when the app crashes.</p>
  
  <p>This code is working if Wi-Fi is on but it's not working at all if Wi-Fi is off..</p>
  
  <pre><code>firebase.database().ref('users/test/connected').onDisconnect().set(false)
  </code></pre>
  
  <p>Any ideas?</p>