Drop support for older Barback versions.

test/transformer/exclusion/works_on_transformer_group_test.dart

Index: test/transformer/exclusion/works_on_transformer_group_test.dart
diff --git a/test/transformer/exclusion/works_on_transformer_group_test.dart b/test/transformer/exclusion/works_on_transformer_group_test.dart
index dfd8ed3ed788ea9d7e08910321a284735228e6a5..9ccf3b091a6965efa013ff9c1fb7572cf93dc497 100644
--- a/test/transformer/exclusion/works_on_transformer_group_test.dart
+++ b/test/transformer/exclusion/works_on_transformer_group_test.dart
@@ -21,38 +21,36 @@ class RewriteGroup implements TransformerGroup {
 """;
 
 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();
-
-      createLockFile('myapp', pkg: ['barback']);
-
-      pubServe();
-      requestShould404("a.out");
-      requestShouldSucceed("b.out", "b.txt.out");
-      requestShould404("c.out");
-      endPubServe();
-    });
-  });
+   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']);
+
+     pubServe();
+     requestShould404("a.out");
+     requestShouldSucceed("b.out", "b.txt.out");
+     requestShould404("c.out");
+     endPubServe();
+   });
 }