Port of github.com/polymer/polymer.

pkg/polymer/lib/transformer.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS 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.
 
 /** Transfomers used for pub-serve and pub-deploy. */
 // TODO(sigmund): move into a plugin directory when pub supports it.
 library polymer.src.transform;
 
+import 'package:barback/barback.dart';
 import 'package:observe/transform.dart';
 import 'src/build/code_extractor.dart';
 import 'src/build/import_inliner.dart';
 import 'src/build/script_compactor.dart';
 import 'src/build/polyfill_injector.dart';
 import 'src/build/common.dart';
 
 export 'src/build/code_extractor.dart';
 export 'src/build/import_inliner.dart';
 export 'src/build/script_compactor.dart';
 export 'src/build/polyfill_injector.dart';
 export 'src/build/common.dart' show TransformOptions;
 
 /** Creates phases to deploy a polymer application. */
 List<List<Transformer>> createDeployPhases(TransformOptions options) {
   return [
     [new InlineCodeExtractor(options)],
     [new ObservableTransformer()],
     [new ImportedElementInliner(options)],
     [new ScriptCompactor(options)],
     [new PolyfillInjector(options)]
   ];
 }