Update charted to 0.4.8 and roll

packages/quiver/lib/src/iterables/infinite_iterable.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;
 
-/**
- * A base class for [Iterable]s of infinite length that throws
- * [UnsupportedError] for methods that would require the Iterable to terminate.
- */
+/// A base class for [Iterable]s of infinite length that throws
+/// [UnsupportedError] for methods that would require the Iterable to
+/// terminate.
 abstract class InfiniteIterable<T> extends IterableBase<T> {
   bool get isEmpty => false;
 
   bool get isNotEmpty => true;
 
   T get last => throw new UnsupportedError('last');
 
   int get length => throw new UnsupportedError('length');
 
   T get single => throw new StateError('single');
 
   bool every(bool f(T element)) => throw new UnsupportedError('every');
 
-  bool fold(initialValue, combine(previousValue, T element)) =>
+  T1 fold<T1>(T1 initialValue, T1 combine(T1 previousValue, T element)) =>
       throw new UnsupportedError('fold');
 
   void forEach(void f(T element)) => throw new UnsupportedError('forEach');
 
   String join([String separator = '']) => throw new UnsupportedError('join');
 
   T lastWhere(bool test(T value), {T orElse()}) =>
       throw new UnsupportedError('lastWhere');
 
   T reduce(T combine(T value, T element)) =>
       throw new UnsupportedError('reduce');
 
   List<T> toList({bool growable: true}) => throw new UnsupportedError('toList');
 
   Set<T> toSet() => throw new UnsupportedError('toSet');
 }