remove un-needed code.

src/Avalonia.Controls/ToggleSwitch.cs

@@ -1,10 +1,7 @@
 using Avalonia.Controls.Primitives;
-using Avalonia.Controls.Mixins;
-using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Templates;
 using Avalonia.LogicalTree;
 
-
 namespace Avalonia.Controls
 {
     /// <summary>
@@ -60,18 +57,6 @@ namespace Avalonia.Controls
             set { SetValue(OffContentProperty, value); }
         }
 
-        public IContentPresenter OffContentPresenter
-        {
-            get;
-            private set;
-        }
-
-        public IContentPresenter OnContentPresenter
-        {
-            get;
-            private set;
-        }
-
         /// <summary>
         /// Gets or Sets the <see cref="IDataTemplate"/> used to display the <see cref="OffContent"/>.
         /// </summary>
@@ -115,24 +100,6 @@ namespace Avalonia.Controls
                 LogicalChildren.Add(newChild);
             }
         }
-
-        protected override bool RegisterContentPresenter(IContentPresenter presenter)
-        {
-            var result = base.RegisterContentPresenter(presenter);
-
-            if (presenter.Name == "Part_OnContentPresenter")
-            {
-                OnContentPresenter = presenter;
-                result = true;
-            }
-            else if (presenter.Name == "PART_OffContentPresenter")
-            {
-                OffContentPresenter = presenter;
-                result = true;
-            }
-
-            return result;
-        }
     }
 }