Rephrased AV1830 to mention the current sync context

Closed dennisdoomen#163

_pages/1800_PerformanceGuidelines.md

@@ -39,4 +39,4 @@ Now when an ASP.NET MVC controller action does this:
 		return View(data);  
 	}
 
-You end up with a deadlock. Why? Because the `Result` property getter will block until the `async` operation has completed, but since an `async` method will automatically marshal the result back to the original thread and ASP.NET uses a single-threaded synchronization context, they'll be waiting on each other. A similar problem can also happen on WPF, Silverlight or a Windows Store C#/XAML app. Read more about this [here](http://blogs.msdn.com/b/pfxteam/archive/2011/01/13/10115163.aspx).
+You end up with a deadlock. Why? Because the `Result` property getter will block until the `async` operation has completed, but since an `async` method _could_ automatically marshal the result back to the original thread (depending on the current `SynchronizationContext` or `TaskScheduler`) and ASP.NET uses a single-threaded synchronization context, they'll be waiting on each other. A similar problem can also happen on UWP, WPF or a Windows Store C#/XAML app. Read more about this [here](http://blogs.msdn.com/b/pfxteam/archive/2011/01/13/10115163.aspx).