Update charted to 0.4.8 and roll

packages/quiver_iterables/lib/src/count.dart

-// Copyright 2013 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.iterables;
-
-/// Returns an infinite [Iterable] of [num]s, starting from [start] and
-/// increasing by [step].
-Iterable<num> count([num start = 0, num step = 1]) sync* {
-  while (true) {
-    yield start;
-    start += step;
-  }
-}