Drop support for older Barback versions.

test/transformer/can_use_has_input_test.dart

Index: test/transformer/can_use_has_input_test.dart
diff --git a/test/transformer/can_use_has_input_test.dart b/test/transformer/can_use_has_input_test.dart
index b2b4ab59fcf34303d484e64f59404007f8c66714..1e497445771e4516c4b541417c98d3cfddaa0865 100644
--- a/test/transformer/can_use_has_input_test.dart
+++ b/test/transformer/can_use_has_input_test.dart
@@ -33,26 +33,24 @@ class RewriteTransformer extends Transformer {
 """;
 
 main() {
-  withBarbackVersions("any", () {
-    integration("a transform can use hasInput", () {
-      d.dir(appPath, [
-        d.pubspec({
-          "name": "myapp",
-          "transformers": ["myapp/src/transformer"]
-        }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", TRANSFORMER)
-        ])]),
-        d.dir("web", [
-          d.file("foo.txt", "foo")
-        ])
-      ]).create();
-
-      createLockFile('myapp', pkg: ['barback']);
-
-      pubServe();
-      requestShouldSucceed("foo.out", "primary: true, secondary: false");
-      endPubServe();
-    });
-  });
+   integration("a transform can use hasInput", () {
+     d.dir(appPath, [
+       d.pubspec({
+         "name": "myapp",
+         "transformers": ["myapp/src/transformer"]
+       }),
+       d.dir("lib", [d.dir("src", [
+         d.file("transformer.dart", TRANSFORMER)
+       ])]),
+       d.dir("web", [
+         d.file("foo.txt", "foo")
+       ])
+     ]).create();
+
+     createLockFile('myapp', pkg: ['barback']);
+
+     pubServe();
+     requestShouldSucceed("foo.out", "primary: true, secondary: false");
+     endPubServe();
+   });
 }