title: PushAsync not working with ContentPage
body: <p>Trying to navigate from one page to another page by using</p>
  
  <pre><code>await Navigation.PushAsync(new Page2());
  </code></pre>
  
  <p>But getting,</p>
  
  <blockquote>
    <p>System.InvalidOperationException: PushAsync is not supported globally on Android, please use a NavigationPage.</p>
  </blockquote>
  
  <pre><code>new NavigationPage(new Page2());
  </code></pre>
  
  <p>And</p>
  
  <pre><code>MainPage = new NavigationPage(new App6.Views.SplashPage());
  </code></pre>
  
  <p>Also not working</p>