Use the new test runner.

test/global/activate/supports_version_solver_backtracking_test.dart

 // Copyright (c) 2014, 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 'package:scheduled_test/scheduled_test.dart';
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
-  initConfig();
   integration('performs verison solver backtracking if necessary', () {
     servePackages((builder) {
       builder.serve("foo", "1.1.0", pubspec: {
         "environment": {"sdk": ">=0.1.2 <0.2.0"}
       });
       builder.serve("foo", "1.2.0", pubspec: {
         "environment": {"sdk": ">=0.1.3 <0.2.0"}
       });
     });
 
     schedulePub(args: ["global", "activate", "foo"]);
 
     // foo 1.2.0 won't be picked because its SDK constraint conflicts with the
     // dummy SDK version 0.1.2+3.
     d.dir(cachePath, [
       d.dir('global_packages', [
         d.dir('foo', [d.matcherFile('pubspec.lock', contains('1.1.0'))])
       ])
     ]).validate();
   });
 }