Revert "Parts must start with 'part of'" and "Attempt to fix VM build"

dart/tests/lib/crypto/sha256_long_test_vectors.dart

Index: dart/tests/lib/crypto/sha256_long_test_vectors.dart
diff --git a/dart/tests/lib/crypto/sha256_long_test_vectors.dart b/dart/tests/lib/crypto/sha256_long_test_vectors.dart
index a0e97b65e13e52dacbb04983451a5af37157e26e..e67c7a50c26b69f9a61afbb69b205555b92ff7c1 100644
--- a/dart/tests/lib/crypto/sha256_long_test_vectors.dart
+++ b/dart/tests/lib/crypto/sha256_long_test_vectors.dart
@@ -1,5 +1,3 @@
-part of sha256_test;
-
 // Copyright (c) 2012, 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.