Revert "Simplify tests under utils/tests to follow StandardTestSuite

utils/tests/import_mapper/c.dart

Index: utils/tests/import_mapper/c.dart
===================================================================
--- utils/tests/import_mapper/c.dart	(revision 6209)
+++ utils/tests/import_mapper/c.dart	(working copy)
@@ -1,10 +0,0 @@
-// 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.
-
-/** A dummy library for testing import_mapper. */
-#library('c');
-
-/** Circular import. */
-#import('b.dart');
-