Update charted to 0.4.8 and roll

packages/quiver/lib/src/async/collect.dart

Index: packages/quiver/lib/src/async/collect.dart
diff --git a/packages/quiver/lib/src/async/collect.dart b/packages/quiver/lib/src/async/collect.dart
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+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+part of quiver.async;
+
+/// Returns a stream of completion events for the input [futures].
+///
+/// Successfully completed futures yield data events, while futures completed
+/// with errors yield error events.
+///
+/// The iterator obtained from [futures] is only advanced once the previous
+/// future completes and yields an event.  Thus, lazily creating the futures is
+/// supported, for example:
+///
+///     collect(files.map((file) => file.readAsString()));
+///
+/// If you need to modify [futures], or a backing collection thereof, before
+/// the returned stream is done, pass a copy instead to avoid a
+/// [ConcurrentModificationError]:
+///
+///     collect(files.toList().map((file) => file.readAsString()));
+Stream collect(Iterable futures) =>
+    new Stream.fromIterable(futures).asyncMap((f) => f);