Made SendPort a Capability.

tests/isolate/capability_test.dart

 // Copyright (c) 2014, 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 "dart:isolate";
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 
 void main() {
   asyncStart();
-  var c1 = new Capability();
-  var c2 = new Capability();
-  Expect.notEquals(c1, c2);
 
-  var receive = new RawReceivePort();
-  receive.sendPort.send(c1);
-  receive.handler = (c3) {
-    Expect.equals(c3, c1);
-    Expect.notEquals(c3, c2);
-    asyncEnd();
-  };
+  test(c1, c2) {
+    asyncStart();
+    Expect.notEquals(c1, c2);
+    var receive = new RawReceivePort();
+    receive.sendPort.send(c1);
+    receive.handler = (c3) {
+      Expect.equals(c3, c1);
+      Expect.notEquals(c3, c2);
+      receive.close();
+      asyncEnd();
+    };
+  }
+  Capability c1 = new Capability();
+  Capability c2 = new Capability();
+  Capability c3 = (new RawReceivePort()..close()).sendPort;
+  Capability c4 = (new RawReceivePort()..close()).sendPort;
+  test(c1, c2);
+  test(c3, c4);
+  test(c1, c3);
+  asyncEnd();
 }