calling InvalidateVisual() only when needed

src/Avalonia.Controls/Control.cs

@@ -322,6 +322,8 @@ namespace Avalonia.Controls
                 {
                     InvalidateFlowDirection();
                     NotifyDescendantFlowDirection();
+
+                    InvalidateVisual();
                 }
             }
         }

src/Avalonia.Visuals/Visual.cs

@@ -114,8 +114,7 @@ namespace Avalonia
                 ClipProperty,
                 ClipToBoundsProperty,
                 IsVisibleProperty,
-                OpacityProperty,
+                OpacityProperty);
-                IsMirrorTransformProperty);
             RenderTransformProperty.Changed.Subscribe(RenderTransformChanged);
             ZIndexProperty.Changed.Subscribe(ZIndexChanged);
         }