Expose Zones.

sdk/lib/async/future.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.
 
 part of dart.async;
 
 /**
  * An object representing a delayed computation.
  *
  * A [Future] is used to obtain a not yet
@@ skipping 176 matching lines @@
    * Returns a future which will complete once all the futures in a list are
    * complete. If any of the futures in the list completes with an error,
    * the resulting future also completes with an error. Otherwise the value
    * of the returned future will be a list of all the values that were produced.
    */
   static Future<List> wait(Iterable<Future> futures) {
     Completer completer;
     // List collecting values from the futures.
     // Set to null if an error occurs.
     List values;
-    void handleError(error) {
+
+    handleError(error) {
       if (values != null) {
         values = null;
         completer.completeError(error);
       }
+      return null;
     }
+
     // As each future completes, put its value into the corresponding
     // position in the list of values.
     int remaining = 0;
     for (Future future in futures) {
       int pos = remaining++;
       future.catchError(handleError).then((Object value) {
         if (values == null) return null;
         values[pos] = value;
         remaining--;
         if (remaining == 0) {
@@ skipping 145 matching lines @@
    */
   Stream<T> asStream();
 }
 
 /**
  * A way to produce Future objects and to complete them later
  * with a value or error.
  *
  * If you already have a Future, you probably don't need a Completer.
  * Instead, you can usually use [Future.then], which returns a Future:
- * 
+ *
  *     Future doStuff(){
  *       return someAsyncOperation().then((result) {
  *         // Do something.
  *       });
  *     }
  *
  * If you do need to create a Future from scratch—for example,
  * when you're converting a callback-based API into a Future-based
  * one—you can use a Completer as follows:
  *
@@ skipping 86 matching lines @@
    *
    * The argument [exception] must not be `null`.
    */
   void completeError(Object exception, [Object stackTrace]);
 
   /**
    * Whether the future has been completed.
    */
   bool get isCompleted;
 }