Update charted to 0.4.8 and roll

packages/async/lib/src/delegate/stream_consumer.dart

Index: packages/async/lib/src/delegate/stream_consumer.dart
diff --git a/packages/async/lib/src/delegate/stream_consumer.dart b/packages/async/lib/src/delegate/stream_consumer.dart
index 8162db6d8ec7886befc3902e664de3d2170453d4..ba8304085095019e0d4de2cccbfd7badc9949a33 100644
--- a/packages/async/lib/src/delegate/stream_consumer.dart
+++ b/packages/async/lib/src/delegate/stream_consumer.dart
@@ -2,8 +2,6 @@
 // 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 async.delegate.stream_consumer;
-
 import 'dart:async';
 
 /// Simple delegating wrapper around a [StreamConsumer].
@@ -14,8 +12,20 @@ class DelegatingStreamConsumer<T> implements StreamConsumer<T> {
   final StreamConsumer _consumer;
 
   /// Create a delegating consumer forwarding calls to [consumer].
-  DelegatingStreamConsumer(StreamConsumer consumer)
-      : _consumer = consumer;
+  DelegatingStreamConsumer(StreamConsumer<T> consumer) : _consumer = consumer;
+
+  DelegatingStreamConsumer._(this._consumer);
+
+  /// Creates a wrapper that coerces the type of [consumer].
+  ///
+  /// Unlike [new StreamConsumer], this only requires its argument to be an
+  /// instance of `StreamConsumer`, not `StreamConsumer<T>`. This means that
+  /// calls to [addStream] may throw a [CastError] if the argument type doesn't
+  /// match the reified type of [consumer].
+  static StreamConsumer<T> typed<T>(StreamConsumer consumer) =>
+      consumer is StreamConsumer<T>
+          ? consumer
+          : new DelegatingStreamConsumer._(consumer);
 
   Future addStream(Stream<T> stream) => _consumer.addStream(stream);