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

pkg/barback/lib/src/asset_cascade.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.asset_cascade;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'asset.dart';
@@ skipping 205 matching lines @@
       // Process that phase and then loop onto the next.
       return future.then((_) => _process());
     });
   }
 
   /// Processes the current batch of changes to source assets.
   Future _processSourceChanges() {
     // Always pump the event loop. This ensures a bunch of synchronous source
     // changes are processed in a single batch even when the first one starts
     // the build process.
-    return new Future(() {
+    return newFuture(() {
       if (_sourceChanges == null) return null;
 
       // Take the current batch to ensure it doesn't get added to while we're
       // processing it.
       var changes = _sourceChanges;
       _sourceChanges = null;
 
       var updated = new AssetSet();
       var futures = [];
       for (var id in changes.updated) {
@@ skipping 50 matching lines @@
       msg.write(prefixLines(error.toString()));
       if (stackTrace != null) {
         msg.write("\n\n");
         msg.write("Stack trace:\n");
         msg.write(prefixLines(stackTrace.toString()));
       }
       return msg.toString();
     }).join("\n\n");
   }
 }