Remove reflection usage from Shape AffectsGeometry calls.

src/Avalonia.Controls/Shapes/Shape.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
-using System.Reflection;
 using Avalonia.Collections;
 using Avalonia.Media;
 
@@ -166,10 +165,7 @@ namespace Avalonia.Controls.Shapes
             {
                 property.Changed.Subscribe(e =>
                 {
-                    var senderType = e.Sender.GetType().GetTypeInfo();
+                    if (e.Sender is TShape)
-                    var affectedType = typeof(TShape).GetTypeInfo();
-
-                    if (affectedType.IsAssignableFrom(senderType))
                     {
                         AffectsGeometryInvalidate(e);
                     }