First pass at build dependency graph for barback.

pkg/barback/lib/barback.dart

Index: pkg/barback/lib/barback.dart
diff --git a/tests/compiler/dart2js_extra/deferred/deferred_semantics_test.dart b/pkg/barback/lib/barback.dart
similarity index 51%
copy from tests/compiler/dart2js_extra/deferred/deferred_semantics_test.dart
copy to pkg/barback/lib/barback.dart
index 140faca3f8479b47e297b51ee4201a0a9f928b31..62fdc145fd020d5ae1b24506121b3595228b224a 100644
--- a/tests/compiler/dart2js_extra/deferred/deferred_semantics_test.dart
+++ b/pkg/barback/lib/barback.dart
@@ -2,14 +2,14 @@
 // 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.
 
-// Test that deferred loading requires same library names.
+library barback;
 
 import 'dart:async';
-
-@lazy  /// 01: compile-time error
-import 'deferred_function_library.dart';
-
-const lazy = const DeferredLibrary('fisk');
-
-main() {
-}
+import 'dart:io';
+
+export 'src/asset.dart';
+export 'src/asset_id.dart';
+export 'src/asset_provider.dart';
+export 'src/errors.dart';
+export 'src/transform.dart' show Transform;
+export 'src/transformer.dart';