[Modify] Polish it

websocket-sharp/Net/ResponseStream.cs

@@ -238,21 +238,27 @@ namespace WebSocketSharp.Net
         return;
 
       _disposed = true;
-      if (!force && flush (true)) {
+
+      if (!force) {
+        if (flush (true)) {
           _response.Close ();
+
+          _response = null;
+          _stream = null;
+
+          return;
         }
-      else {
+      }
+
       if (_sendChunked) {
         var last = getChunkSizeBytes (0, true);
         _write (last, 0, last.Length);
       }
 
       _body.Dispose ();
-        _body = null;
-
       _response.Abort ();
-      }
 
+      _body = null;
       _response = null;
       _stream = null;
     }