Drop support for older Barback versions.

test/transformer/asset_not_found_exceptions_are_detectable_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 'dart:convert';
 
 import 'package:scheduled_test/scheduled_stream.dart';
 
@@ skipping 20 matching lines @@
           JSON.encode({
         'package': error.id.package,
         'path': error.id.path
       })));
     });
   }
 }
 """;
 
 main() {
-  withBarbackVersions("any", () {
-    integration("AssetNotFoundExceptions are detectable", () {
-      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();
+  integration("AssetNotFoundExceptions are detectable", () {
+    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']);
+    createLockFile('myapp', pkg: ['barback']);
 
-      var server = pubServe();
-      requestShouldSucceed("foo.txt", JSON.encode({
-        "package": "myapp",
-        "path": "nonexistent"
-      }));
-      endPubServe();
+    var server = pubServe();
+    requestShouldSucceed("foo.txt", JSON.encode({
+      "package": "myapp",
+      "path": "nonexistent"
+    }));
+    endPubServe();
 
-      // Since the AssetNotFoundException was caught and handled, the server
-      // shouldn't print any error information for it.
-      server.stderr.expect(isDone);
-    });
+    // Since the AssetNotFoundException was caught and handled, the server
+    // shouldn't print any error information for it.
+    server.stderr.expect(isDone);
   });
 }