isolate will all have been processed.
  The shutdown should happen no later than if sent with
  <code>beforeNextEvent</code>.
  It may happen earlier if the system has a way to shut down cleanly
  at an earlier time, even during the execution of another event.</li><li><code>beforeNextEvent</code>: The shutdown is scheduled for the next time
  control returns to the event loop of the receiving isolate,
  after the current event, and any already scheduled control events,
  are completed.</li></ul>
<p>If <a hr