test rename overhaul: step 3 _tests.dart => _test.dart

utils/tests/css/declaration_test.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.
 
 #library("declaration_tests");
 #import("../../css/css.dart");
 
 void main() {
   initCssWorld();
 
@@ skipping 229 matching lines @@
     "}\n";
 
   Parser parser =
     new Parser(new SourceFile(SourceFile.IN_MEMORY_FILE, scss));
 
   Stylesheet stylesheet = parser.parse();
   Expect.isNotNull(stylesheet);
 
   Expect.equals(generated, stylesheet.toString());
 }