Update pub to use new import syntax.

utils/tests/pub/install/git/unlock_if_incompatible_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('pub_tests');
+library pub_tests;
 
-#import('dart:io');
+import 'dart:io';
 
-#import('../../test_pub.dart');
-#import('../../../../../pkg/unittest/unittest.dart');
+import '../../test_pub.dart';
+import '../../../../../pkg/unittest/unittest.dart';
 
 main() {
   test('updates a locked Git package with a new incompatible constraint', () {
     ensureGit();
 
     git('foo.git', [
       libDir('foo'),
       libPubspec('foo', '0.5.0')
     ]).scheduleCreate();
 
@@ skipping 20 matching lines @@
 
     dir(packagesPath, [
       dir('foo', [
         file('foo.dart', 'main() => "foo 1.0.0";')
       ])
     ]).scheduleValidate();
 
     run();
   });
 }