Drop support for older Barback versions.

test/transformer/fails_to_load_a_file_that_defines_no_transforms_test.dart

Index: test/transformer/fails_to_load_a_file_that_defines_no_transforms_test.dart
diff --git a/test/transformer/fails_to_load_a_file_that_defines_no_transforms_test.dart b/test/transformer/fails_to_load_a_file_that_defines_no_transforms_test.dart
index dd26b899582dbac206ada5bcd3e8f1beaff1f909..b42899399f91ce4dfcf9cc63817a5201066d2d87 100644
--- a/test/transformer/fails_to_load_a_file_that_defines_no_transforms_test.dart
+++ b/test/transformer/fails_to_load_a_file_that_defines_no_transforms_test.dart
@@ -12,25 +12,23 @@ import '../test_pub.dart';
 import '../serve/utils.dart';
 
 main() {
-  withBarbackVersions("any", () {
-    integration("fails to load a file that defines no transforms", () {
-      d.dir(appPath, [
-        d.pubspec({
-          "name": "myapp",
-          "transformers": ["myapp/transformer"]
-        }),
-        d.dir("lib", [
-          d.file("transformer.dart", "library does_nothing;")
-        ])
-      ]).create();
+  integration("fails to load a file that defines no transforms", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "transformers": ["myapp/transformer"]
+      }),
+      d.dir("lib", [
+        d.file("transformer.dart", "library does_nothing;")
+      ])
+    ]).create();
 
-      createLockFile('myapp', pkg: ['barback']);
+    createLockFile('myapp', pkg: ['barback']);
 
-      var pub = startPubServe();
-      pub.stderr.expect(startsWith('No transformers were defined in '));
-      pub.stderr.expect(startsWith('required by myapp.'));
-      pub.shouldExit(1);
-      pub.stderr.expect(never(contains('This is an unexpected error')));
-    });
+    var pub = startPubServe();
+    pub.stderr.expect(startsWith('No transformers were defined in '));
+    pub.stderr.expect(startsWith('required by myapp.'));
+    pub.shouldExit(1);
+    pub.stderr.expect(never(contains('This is an unexpected error')));
   });
 }