Expose aggregate transformers in barback.

pkg/barback/lib/src/transformer/aggregate_transform.dart

 // Copyright (c) 2014, 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.
 
 library barback.transformer.aggregate_transform;
 
 import 'dart:async';
 import 'dart:convert';
 
 import '../asset/asset.dart';
@@ skipping 11 matching lines @@
 
   /// The set of outputs emitted by the transformer.
   final _outputs = new AssetSet();
 
   /// The transform key.
   ///
   /// This is the key returned by [AggregateTransformer.classifyPrimary] for all
   /// the assets in this transform.
   String get key => _node.key;
 
+  /// The package in which this transform is running.
+  String get package => _node.phase.cascade.package;
+
   /// The stream of primary inputs that will be processed by this transform.
   ///
   /// This is exposed as a stream so that the transformer can start working
   /// before all its inputs are available. The stream is closed not just when
   /// all inputs are provided, but when barback is confident no more inputs will
   /// be forthcoming.
   ///
   /// A transformer may complete its `apply` method before this stream is
   /// closed. For example, it may know that each key will only have two inputs
   /// associated with it, and so use `transform.primaryInputs.take(2)` to access
@@ skipping 101 matching lines @@
 
   /// Returns whether an input with the given [id] was added via [addInput].
   bool addedId(AssetId id) {
     return transform._emittedPrimaryInputs.ids.contains(id);
   }
 
   void done() {
     transform._inputController.close();
   }
 }