remove AppContext switch

src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/HostVisual.cs

@@ -404,8 +404,7 @@ private void DisconnectHostedVisualOnAllChannels()
                 // Adding commands to a channel is not thread-safe,
                 // we must do the actual work on the same dispatcher thread
                 // where the connection happened.
-                if (CoreAppContextSwitches.HostVisualDisconnectsOnWrongThread ||
-                    (channelDispatcher != null && channelDispatcher.CheckAccess()))
+                if (channelDispatcher != null && channelDispatcher.CheckAccess())
                 {
                     Disconnect(channel,
                                channelDispatcher,
@@ -519,10 +518,7 @@ private bool DoPendingDisconnect(DUCE.Channel channel)
                                 DUCE.ResourceHandle targetHandle,
                                 DUCE.MultiChannelResource contentRoot)
         {
-            if (!CoreAppContextSwitches.HostVisualDisconnectsOnWrongThread)
-            {
-                channelDispatcher.VerifyAccess();
-            }
+            channelDispatcher.VerifyAccess();
 
             DUCE.CompositionNode.RemoveChild(
                 hostHandle,