Make Streams also cosider a thrown AsyncError a rethrow.

tests/lib/async/stream_controller_test.dart

 // Copyright (c) 2011, 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.
 
 // Test the basic StreamController and StreamController.singleSubscription.
 library stream_controller_test;
 
 import 'dart:async';
 import 'event_helper.dart';
 
@@ skipping 45 matching lines @@
   actualEvents = new Events.capture(c.mappedBy((v) => "$v$v"));
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 
   // Test handleError.
   c = new StreamController();
   expectedEvents = new Events()..add("ab")..error("[foo]");
   sentEvents = new Events()..add("ab")..error("foo")..add("ab")..close();
   actualEvents = new Events.capture(c.handleError((v) {
         if (v.error is String) {
-          return new AsyncError("[${v.error}]",
+          throw new AsyncError("[${v.error}]",
                                 "other stack");
         }
       }), unsubscribeOnError: true);
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 
   // reduce is tested asynchronously and therefore not in this file.
 
   // Test expand
   c = new StreamController();
@@ skipping 31 matching lines @@
                            ..add("snugglefluffy")
                            ..add(7)
                            ..add("42")
                            ..error("not FormatException")  // Unsubscribes.
                            ..close();
   expectedEvents = new Events()..add(42)..error("not FormatException");
   actualEvents = new Events.capture(
       c.where((v) => v is String)
        .mappedBy((v) => int.parse(v))
        .handleError((v) {
-          if (v.error is! FormatException) return v;
+          if (v.error is! FormatException) throw v;
         })
        .where((v) => v > 10),
       unsubscribeOnError: true);
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 
   // Test subscription changes while firing.
   c = new StreamController();
   var sink = c.sink;
   var stream = c.stream;
@@ skipping 67 matching lines @@
   actualEvents = new Events.capture(c.mappedBy((v) => "$v$v"));
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 
   // Test handleError.
   c = new StreamController.singleSubscription();
   expectedEvents = new Events()..add("ab")..error("[foo]");
   sentEvents = new Events()..add("ab")..error("foo")..add("ab")..close();
   actualEvents = new Events.capture(c.handleError((v) {
         if (v.error is String) {
-          return new AsyncError("[${v.error}]",
+          throw new AsyncError("[${v.error}]",
                                 "other stack");
         }
       }), unsubscribeOnError: true);
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 
   // reduce is tested asynchronously and therefore not in this file.
 
   // Test expand
   c = new StreamController.singleSubscription();
@@ skipping 43 matching lines @@
                            ..add("snugglefluffy")
                            ..add(7)
                            ..add("42")
                            ..error("not FormatException")  // Unsubscribes.
                            ..close();
   expectedEvents = new Events()..add(42)..error("not FormatException");
   actualEvents = new Events.capture(
       c.where((v) => v is String)
        .mappedBy((v) => int.parse(v))
        .handleError((v) {
-          if (v.error is! FormatException) return v;
+          if (v.error is! FormatException) throw v;
         })
        .where((v) => v > 10),
       unsubscribeOnError: true);
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 
   // Test that only one subscription is allowed.
   c = new StreamController.singleSubscription();
   var sink = c.sink;
   var stream = c.stream;
@@ skipping 71 matching lines @@
   actualEvents = new Events.capture(c.distinct((a, b) => a < b));
   sentEvents.replay(c);
   Expect.listEquals(expectedEvents.events, actualEvents.events);
 }
 
 main() {
   testController();
   testSingleController();
   testExtraMethods();
 }