dart-lang#993. [ffi] nullptr test added

LibTest/ffi/nullptr/nullptr_A01_t01.dart

@@ -0,0 +1,18 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion Pointer<Never> nullptr
+/// final
+/// Represents a pointer into the native C memory corresponding to 'NULL', e.g.
+/// a pointer with address 0.
+///
+/// @description Checks that this property represents a pointer with address 0
+/// @author sgrekhov22@gmail.com
+
+import "dart:ffi";
+import "../../../Utils/expect.dart";
+
+void main() {
+  Expect.equals(0, nullptr.address);
+}