Drop support for older Barback versions.

test/transformer/exclusion/works_on_transformer_group_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.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;
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import '../../serve/utils.dart';
 
 const GROUP = """
 import 'package:barback/barback.dart';
 
 import 'transformer.dart';
 
 class RewriteGroup implements TransformerGroup {
   RewriteGroup.asPlugin();
 
   Iterable<Iterable> get phases => [[new RewriteTransformer.asPlugin()]];
 }
 """;
 
 main() {
-  withBarbackVersions("any", () {
-    integration("works on a transformer group", () {
-      d.dir(appPath, [
-        d.pubspec({
-          "name": "myapp",
-          "transformers": [
-            {
-              "myapp/src/group": {
-                "\$include": ["web/a.txt", "web/b.txt"],
-                "\$exclude": "web/a.txt"
-              }
-            }
-          ]
-        }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", REWRITE_TRANSFORMER),
-          d.file("group.dart", GROUP)
-        ])]),
-        d.dir("web", [
-          d.file("a.txt", "a.txt"),
-          d.file("b.txt", "b.txt"),
-          d.file("c.txt", "c.txt")
-        ])
-      ]).create();
+   integration("works on a transformer group", () {
+     d.dir(appPath, [
+       d.pubspec({
+         "name": "myapp",
+         "transformers": [
+           {
+             "myapp/src/group": {
+               "\$include": ["web/a.txt", "web/b.txt"],
+               "\$exclude": "web/a.txt"
+             }
+           }
+         ]
+       }),
+       d.dir("lib", [d.dir("src", [
+         d.file("transformer.dart", REWRITE_TRANSFORMER),
+         d.file("group.dart", GROUP)
+       ])]),
+       d.dir("web", [
+         d.file("a.txt", "a.txt"),
+         d.file("b.txt", "b.txt"),
+         d.file("c.txt", "c.txt")
+       ])
+     ]).create();
 
-      createLockFile('myapp', pkg: ['barback']);
+     createLockFile('myapp', pkg: ['barback']);
 
-      pubServe();
-      requestShould404("a.out");
-      requestShouldSucceed("b.out", "b.txt.out");
-      requestShould404("c.out");
-      endPubServe();
-    });
-  });
+     pubServe();
+     requestShould404("a.out");
+     requestShouldSucceed("b.out", "b.txt.out");
+     requestShould404("c.out");
+     endPubServe();
+   });
 }