title: Validating formGroup which contains asyncValidator while in PENDING state
body: <p>Inside a guard, I am trying to check if a form group is valid.</p>
  
  <p>The form group contains an async validator and is in PENDING state when I am trying to check if it is valid inside the canActivate method.</p>
  
  <p>Guard:</p>
  
  <pre><code>canActivate()
  ...
  if (formGroup.valid) {
      // do stuff
  }
  ...
  </code></pre>
  
  <p>How can I wait for the async validator to complete? </p>