Make unittest follow the new package layout.

utils/tests/pub/version_test.dart

 // 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.
 
 #library('version_test');
 
-#import('../../../pkg/unittest/unittest.dart');
+#import('../../../pkg/unittest/lib/unittest.dart');
 #import('../../pub/utils.dart');
 #import('../../pub/version.dart');
 
 main() {
   final v123 = new Version.parse('1.2.3');
   final v114 = new Version.parse('1.1.4');
   final v124 = new Version.parse('1.2.4');
   final v200 = new Version.parse('2.0.0');
   final v234 = new Version.parse('2.3.4');
   final v250 = new Version.parse('2.5.0');
@@ skipping 404 matching lines @@
 
 Matcher allows(List<Version> versions) =>
     new VersionConstraintMatcher(versions, true);
 
 Matcher doesNotAllow(List<Version> versions) =>
     new VersionConstraintMatcher(versions, false);
 
 throwsIllegalArg(function) {
   expect(function, throwsA((e) => e is IllegalArgumentException));
 }