Update NavigationPage Platform Specifics demo with pre-393 compatible color

Xamarin.Forms.Controls/GalleryPages/PlatformSpecificsGalleries/NavigationPageWindows.cs

@@ -9,7 +9,7 @@ namespace Xamarin.Forms.Controls.GalleryPages.PlatformSpecificsGalleries
 			PushAsync(CreateRoot(restore));
 			WindowsPlatformSpecificsGalleryHelpers.AddToolBarItems(this);
 
-			BarBackgroundColor = Color.CornflowerBlue;
+			BarBackgroundColor = Color.FromHex("6495ED");
 		}
 
 		ContentPage CreateRoot(ICommand restore)