Revise barback logging patch.

pkg/barback/lib/src/phase_forwarder.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.
 
 library barback.phase_forwarder;
 
 import 'dart:async';
 
 import 'asset_node.dart';
-import 'asset_forwarder.dart';
-import 'phase_output.dart';
 
 /// A class that takes care of forwarding assets within a phase.
 ///
 /// Each phase contains one or more channels that process its input assets. The
 /// non-grouped transformers for that phase are one such channel, and each
 /// [TransformerGroup] in that phase is another. For each input asset, each
 /// channel individually decides whether to forward that asset based on whether
 /// that channel uses it. If a channel does decide to forward an asset, we call
 /// that forwarded asset an "intermediate forwarded asset" to distinguish it
 /// from the output of a [PhaseForwarder].
@@ skipping 100 matching lines @@
     // intermediate assets are dirty.
     if (_intermediateAssets.any((asset) => asset.state.isDirty)) {
       if (!_outputController.node.state.isDirty) _outputController.setDirty();
     } else {
       if (!_outputController.node.state.isAvailable) {
         _outputController.setAvailable(_intermediateAssets.first.asset);
       }
     }
   }
 }