title: Undefined class 'AuthResult' in Flutter
body: <p>I have been trying to implement Google login screen using Flutter. </p>
  
  <pre class="lang-dart prettyprint-override"><code>final AuthResult authResult = await _auth.signInWithCredential(credential);
  </code></pre>
  
  <p>The editor, for the line above, says:</p>
  
  <blockquote>
    <p>Undefined class 'AuthResult'</p>
  </blockquote>
  
  <p>How can I fix it? Any help would be very appreciated.</p>