Add zone support to streams.

tests/lib/async/catch_errors27_test.dart

+// Copyright (c) 2013, 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.
+
+import "package:expect/expect.dart";
+import 'dart:async';
+import 'dart:isolate';
+
+main() {
+  // We keep a ReceivePort open until all tests are done. This way the VM will
+  // hang if the callbacks are not invoked and the test will time out.
+  var port = new ReceivePort();
+  var events = [];
+  StreamController controller;
+  Stream stream;
+  // Test that the first listen on a `asBroadcastStream` determines the
+  // zone the subscription lives in. The inner listen happens first, and
+  // the outer listener must not see the error since it would cross a
+  // zone boundary. It is therefore given to the inner `catchErrors`.
+  catchErrors(() {
+    catchErrors(() {
+      controller = new StreamController();
+      stream = controller.stream
+        .map((x) {
+          events.add("map $x");
+          return x + 100;
+        })
+        .asBroadcastStream();
+      stream
+        .transform(new StreamTransformer(
+            handleError: (e, sink) => sink.add("error $e")))
+        .listen((x) { events.add("stream $x"); });
+      runAsync(() {
+        controller.add(1);
+        // Errors are not allowed to traverse boundaries, but in this case the
+        // first listener of the broadcast stream is in the same error-zone. So
+        // this should work.
+        controller.addError(2);
+        controller.close();
+      });
+    }).listen((x) { events.add(x); })
+      .asFuture().then((_) { events.add("inner done"); });
+    stream.listen((x) { events.add("stream2 $x"); });
+  }).listen((x) { events.add("outer: $x"); },
+            onDone: () {
+              Expect.listEquals(["map 1",
+                                 "stream 101",
+                                 "stream2 101",
+                                 "stream error 2",
+                                 2, // Caught by the inner `catchErrors`.
+                                 "inner done",
+                                ],
+                                events);
+              port.close();
+            });
+}