Remove calls to [new Future] work around issue 11911.

pkg/barback/lib/src/transform.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.transform;
 
 import 'dart:async';
 
 import 'asset.dart';
 import 'asset_id.dart';
 import 'asset_node.dart';
 import 'asset_set.dart';
 import 'errors.dart';
 import 'transform_node.dart';
+import 'utils.dart';
 
 /// Creates a [Transform] by forwarding to the private constructor.
 ///
 /// Lets [TransformNode] create [Transforms] without giving a [Transform]
 /// itself a public constructor, which would be visible to external users.
 /// Unlike the [Transform] class, this function is not exported by barback.dart.
 Transform createTransform(TransformNode node, Set<AssetNode> inputs,
                           AssetSet outputs) =>
     new Transform._(node, inputs, outputs);
 
@@ skipping 24 matching lines @@
   /// Gets the asset for the primary input.
   Future<Asset> get primaryInput => getInput(primaryId);
 
   Transform._(this._node, this._inputs, this._outputs);
 
   /// Gets the asset for for an input [id].
   ///
   /// If an input with that ID cannot be found, throws an
   /// [AssetNotFoundException].
   Future<Asset> getInput(AssetId id) {
-    return new Future(() {
+    return newFuture(() {
       var node = _node.phase.inputs[id];
       // TODO(rnystrom): Need to handle passthrough where an asset from a
       // previous phase can be found.
 
       // Throw if the input isn't found. This ensures the transformer's apply
       // is exited. We'll then catch this and report it through the proper
       // results stream.
       if (node == null) throw new MissingInputException(id);
 
       // Keep track of which assets this transform depends on.
       _inputs.add(node);
       return node.asset;
     });
   }
 
   /// Stores [output] as the output created by this transformation.
   ///
   /// A transformation can output as many assets as it wants.
   void addOutput(Asset output) {
     // TODO(rnystrom): This should immediately throw if an output with that ID
     // has already been created by this transformer.
     _outputs.add(output);
   }
 }