title: MissingRuntimeArtifactException on Xamarin.Forms App with .Net Native Toolchain Enabled
body: <p>i've a Xamarin.Forms application (UWP, using .Net Standard 2.0; Target Windows Version: 10 Fall Creators Update), that runs perfect without .NET Native toolchain. But when i enable the .Net Native Toolchain in the project settings, i retrieve exceptions during runtime:</p>
  
  <pre><code>System.Reflection.MissingRuntimeArtifactException: 'Cannot retrieve a MethodInfo for this delegate because the method it targeted (Void Xamarin.Forms.Platform.UWP.Platform.OnPageAlert(Object, AlertArguments)) was not enabled for metadata using the Dynamic attribute. For more information, please visit http://go.microsoft.com/fwlink/?LinkID=616868'
  </code></pre>
  
  <p>It seems that i have to modify the default.rd.xml file in my UWP project. But i don't know exactly how to. </p>
  
  <p>I added </p>
  
  <pre><code>&lt;Type Name="Xamarin.Forms.Platform.UWP.Platform" Serialize="Required All" Dynamic="Required All"/&gt;
  </code></pre>
  
  <p>but with no result. Same exception as before. 
  Can someone give me the hint, how to solve that issue?</p>
  
  <p>cheers,
  Chris</p>