Drop support for older Barback versions.

test/global/run/runs_transformer_test.dart

Index: test/global/run/runs_transformer_test.dart
diff --git a/test/global/run/runs_transformer_test.dart b/test/global/run/runs_transformer_test.dart
index 69aace54ffcc3bddccf42a2970847c36a857171f..ac0489b9277fb9d765e670b19e5c8ff34d6f50ec 100644
--- a/test/global/run/runs_transformer_test.dart
+++ b/test/global/run/runs_transformer_test.dart
@@ -24,24 +24,22 @@ class DartTransformer extends Transformer {
 """;
 
 main() {
-  withBarbackVersions("any", () {
-    integration('runs a global script generated by a transformer', () {
-      makeGlobalPackage("foo", "1.0.0", [
-        d.pubspec({
-          "name": "foo",
-          "version": "1.0.0",
-          "transformers": ["foo/src/transformer"]
-        }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", TRANSFORMER),
-          d.file("primary.in", "")
-        ])])
-      ], pkg: ['barback']);
-
-      var pub = pubRun(global: true, args: ["foo:script"]);
-
-      pub.stdout.expect("generated");
-      pub.shouldExit();
-    });
+  integration('runs a global script generated by a transformer', () {
+    makeGlobalPackage("foo", "1.0.0", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "transformers": ["foo/src/transformer"]
+      }),
+      d.dir("lib", [d.dir("src", [
+        d.file("transformer.dart", TRANSFORMER),
+        d.file("primary.in", "")
+      ])])
+    ], pkg: ['barback']);
+
+    var pub = pubRun(global: true, args: ["foo:script"]);
+
+    pub.stdout.expect("generated");
+    pub.shouldExit();
   });
 }