Update charted to 0.4.8 and roll

packages/quiver/lib/src/async/iteration.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.async;
 
-/**
- * An asynchronous callback that returns a value.
- */
+/// An asynchronous callback that returns a value.
 typedef Future<T> AsyncAction<T>(e);
 
-/**
- * An asynchronous funcuntion that combines an element [e] with a previous value
- * [previous], for use with [reduceAsync].
- */
+/// An asynchronous funcuntion that combines an element [e] with a previous
+/// value [previous], for use with [reduceAsync].
 typedef Future<T> AsyncCombiner<T>(T previous, e);
 
-/**
- * Calls [action] for each item in [iterable] in turn, waiting for the Future
- * returned by action to complete.
- *
- * If the Future completes to [true], iteration continues.
- *
- * The Future returned completes to [true] if the entire iterable was processed,
- * otherwise [false].
- */
+/// Calls [action] for each item in [iterable] in turn, waiting for the Future
+/// returned by action to complete.
+///
+/// If the Future completes to [true], iteration continues.
+///
+/// The Future returned completes to [true] if the entire iterable was
+/// processed, otherwise [false].
 Future doWhileAsync(Iterable iterable, AsyncAction<bool> action) =>
     _doWhileAsync(iterable.iterator, action);
 
-Future _doWhileAsync(
-    Iterator iterator, AsyncAction<bool> action) => (iterator.moveNext())
-    ? action(iterator.current).then((bool result) =>
-        (result) ? _doWhileAsync(iterator, action) : new Future.value(false))
-    : new Future.value(true);
+Future _doWhileAsync(Iterator iterator, AsyncAction<bool> action) async {
+  if (iterator.moveNext()) {
+    return await action(iterator.current)
+        ? _doWhileAsync(iterator, action)
+        : false;
+  }
+  return true;
+}
 
-/**
- * Reduces a collection to a single value by iteratively combining elements
- * of the collection using the provided [combine] function. Similar to
- * [Iterable.reduce], except that [combine] is an async function that returns a
- * [Future].
- */
+/// Reduces a collection to a single value by iteratively combining elements of
+/// the collection using the provided [combine] function. Similar to
+/// [Iterable.reduce], except that [combine] is an async function that returns
+/// a [Future].
 Future reduceAsync(Iterable iterable, initialValue, AsyncCombiner combine) =>
     _reduceAsync(iterable.iterator, initialValue, combine);
 
-Future _reduceAsync(Iterator iterator, currentValue, AsyncCombiner combine) {
+Future _reduceAsync(Iterator iterator, current, AsyncCombiner combine) async {
   if (iterator.moveNext()) {
-    return combine(currentValue, iterator.current)
-        .then((result) => _reduceAsync(iterator, result, combine));
+    var result = await combine(current, iterator.current);
+    return _reduceAsync(iterator, result, combine);
   }
-  return new Future.value(currentValue);
+  return current;
 }
 
-/**
- * Schedules calls to [action] for each element in [iterable]. No more than
- * [maxTasks] calls to [action] will be pending at once.
- */
+/// Schedules calls to [action] for each element in [iterable]. No more than
+/// [maxTasks] calls to [action] will be pending at once.
 Future forEachAsync(Iterable iterable, AsyncAction action, {int maxTasks: 1}) {
   if (maxTasks == null || maxTasks < 1) {
     throw new ArgumentError("maxTasks must be greater than 0, was: $maxTasks");
   }
 
   if (iterable == null) {
     throw new ArgumentError("iterable must not be null");
   }
 
   if (iterable.isEmpty) return new Future.value();
 
   var completer = new Completer();
   var iterator = iterable.iterator;
   int pending = 0;
   bool failed = false;
 
   bool scheduleTask() {
     if (pending < maxTasks && iterator.moveNext()) {
       pending++;
       var item = iterator.current;
       scheduleMicrotask(() {
         var task = action(item);
         task.then((_) {
           pending--;
           if (failed) return;
           if (!scheduleTask() && pending == 0) {
             completer.complete();
           }
-        }).catchError((e) {
+        }).catchError((e, stack) {
           if (failed) return;
           failed = true;
-          completer.completeError(e);
+          completer.completeError(e, stack);
         });
       });
       return true;
     }
     return false;
   }
+
   while (scheduleTask()) {}
   return completer.future;
 }