Ensure that errors have stack traces attached.

pkg/http/lib/src/utils.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library utils;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
@@ skipping 198 matching lines @@
     if (other is! Pair) return false;
     return other.first == first && other.last == last;
   }
 
   int get hashCode => first.hashCode ^ last.hashCode;
 }
 
 /// Configures [future] so that its result (success or exception) is passed on
 /// to [completer].
 void chainToCompleter(Future future, Completer completer) {
-  future.then((v) => completer.complete(v)).catchError((error) {
-    completer.completeError(error);
-  });
+  future.then(completer.complete, onError: completer.completeError);
 }
 
 // TOOD(nweiz): Get rid of this once https://codereview.chromium.org/11293132/
 // is in.
 /// Runs [fn] for each element in [input] in order, moving to the next element
 /// only when the [Future] returned by [fn] completes. Returns a [Future] that
 /// completes when all elements have been processed.
 ///
 /// The return values of all [Future]s are discarded. Any errors will cause the
 /// iteration to stop and will be piped through the return value.
 Future forEachFuture(Iterable input, Future fn(element)) {
   var iterator = input.iterator;
   Future nextElement(_) {
     if (!iterator.moveNext()) return new Future.value();
     return fn(iterator.current).then(nextElement);
   }
   return nextElement(null);
 }