pkg/csslib: use pkg/test and allow latest version of logging pkg

test/visitor_test.dart

 // Copyright (c) 2013, 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 visitor_test;
 
-import 'package:unittest/unittest.dart';
 import 'package:csslib/visitor.dart';
+import 'package:test/test.dart';
+
 import 'testing.dart';
 
 class ClassVisitor extends Visitor {
   final List expectedClasses;
   final Set<String> foundClasses = new Set();
 
   ClassVisitor(this.expectedClasses);
 
   void visitClassSelector(ClassSelector node) {
     foundClasses.add(node.name);
@@ skipping 84 matching lines @@
   expect(errors.isEmpty, true, reason: errors.toString());
 
   final emitted = polyfillPrint('myComponent', s);
   expect(emitted, generated);
 }
 
 main() {
   test('Class Visitors', testClassVisitors);
   test('Polyfill', testPolyFill);
 }