Fixing initialization issue for IOCP handle.

src/System.Net.HttpListener/src/System/Net/Windows/HttpListener.Windows.cs

@@ -1915,7 +1915,7 @@ internal unsafe DisconnectAsyncResult(HttpListener httpListener, ulong connectio
                 _httpListener = httpListener;
                 _connectionId = connectionId;
                 // we can call the Unsafe API here, we won't ever call user code
-                _nativeOverlapped = httpListener._requestQueueBoundHandle.AllocateNativeOverlapped(s_IOCallback, state: this, pinData: null);
+                _nativeOverlapped = httpListener.RequestQueueBoundHandle.AllocateNativeOverlapped(s_IOCallback, state: this, pinData: null);
             }
 
             internal bool StartOwningDisconnectHandling()