Update charted to 0.4.8 and roll

packages/when/README.md

-when [![pub package](http://img.shields.io/pub/v/when.svg)](https://pub.dartlang.org/packages/when) [![Build Status](https://drone.io/github.com/seaneagan/when.dart/status.png)](https://drone.io/github.com/seaneagan/when.dart/latest) [![Coverage Status](https://img.shields.io/coveralls/seaneagan/when.dart.svg)](https://coveralls.io/r/seaneagan/when.dart?branch=master)
-====
-
-It's often useful to provide sync (convenient) and async (concurrent) versions 
-of the same API.  `dart:io` does this with many APIs including [Process.run][] 
-and [Process.runSync][].  Since the sync and async versions do the same thing, 
-much of the logic is the same, with just a few small bits differing in their 
-sync vs. async implementation.
-
-The `when` function allows for registering `onSuccess`, `onError`, and 
-`onComplete` callbacks on another callback which represents that sync/async 
-dependent part of the API.  If the callback is sync (returns a non-`Future` or 
-throws), then the other callbacks are invoked synchronously, otherwise the 
-other callbacks are registered on the returned `Future`.
-
-For example, here's how it can be used to implement sync and async APIs for
-reading a JSON data structure from the file system with file absence handling:
-
-```dart
-import 'dart:async';
-import 'dart:convert';
-import 'dart:io';
-
-import 'package:when/when.dart';
-
-/// Reads and decodes JSON from [path] asynchronously.
-///
-/// If [path] does not exist, returns the result of calling [onAbsent].
-Future readJsonFile(String path, {onAbsent()}) => _readJsonFile(
-    path, onAbsent, (file) => file.exists(), (file) => file.readAsString());
-
-/// Reads and decodes JSON from [path] synchronously.
-///
-/// If [path] does not exist, returns the result of calling [onAbsent].
-readJsonFileSync(String path, {onAbsent()}) => _readJsonFile(
-    path, onAbsent, (file) => file.existsSync(),
-    (file) => file.readAsStringSync());
-
-_readJsonFile(String path, onAbsent(), exists(File file), read(File file)) {
-  var file = new File(path);
-  return when(
-      () => exists(file),
-      onSuccess: (doesExist) => doesExist ?
-          when(() => read(file), onSuccess: JSON.decode) :
-          onAbsent());
-}
-
-main() {
-  var syncJson = readJsonFileSync('foo.json', onAbsent: () => {'foo': 'bar'});
-  print('Sync json: $syncJson');
-  readJsonFile('foo.json', onAbsent: () => {'foo': 'bar'}).then((asyncJson) {
-    print('Async json: $asyncJson');
-  });
-}
-```
-
-[Process.run]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart:io.Process#id_run
-[Process.runSync]: https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart:io.Process#id_runSync