Revert "Simplify tests under utils/tests to follow StandardTestSuite

utils/tests/css/src/DeclarationTest.dart

 // Copyright (c) 2011, 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.
 
 #import("../../../css/css.dart");
 
 class DeclarationTest {
 
   static testMain() {
     initCssWorld();
@@ skipping 235 matching lines @@
     Stylesheet stylesheet = parser.parse();
     Expect.isNotNull(stylesheet);
 
     Expect.equals(generated, stylesheet.toString());
   }
 }
 
 main() {
   DeclarationTest.testMain();
 }