Add support for JS->Dart and Dart->dart via *PortSync.

tests/html/js_interop_4_test.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('JsInterop4Test');
+#import('../../lib/unittest/unittest.dart');
+#import('../../lib/unittest/html_config.dart');
+#import('dart:html');
+#import('dart:isolate');
+
+const testData = const [1, '2', 'true'];
+
+class TestIsolate extends Isolate {
+  TestIsolate() : super();
+
+  void main() {
+    var fun1 = window.lookupPort('fun1');
+    var result = fun1.callSync(testData);
+
+    var fun2 = window.lookupPort('fun2');
+    fun2.callSync(result);
+  }
+}
+
+main() {
+  useHtmlConfiguration();
+
+  // Test that our interop scheme also works from Dart to Dart.
+  test('dart-to-dart-same-isolate', () {
+    var fun = expectAsync1((message) {
+        Expect.listEquals(testData, message);
+        return message.length;
+      });
+
+    var port1 = new ReceivePortSync();
+    port1.receive(fun);
+    window.registerPort('fun', port1.toSendPort());
+
+    var port2 = window.lookupPort('fun');
+    var result = port2.callSync(testData);
+    Expect.equals(3, result);
+  });
+
+  // Test across isolate boundary.
+  test('dart-to-dart-cross-isolate', () {
+    var done = expectAsync0(() {});
+
+    var fun1 = (message) {
+      Expect.listEquals(testData, message);
+      return message.length;
+    };
+
+    var port1 = new ReceivePortSync();
+    port1.receive(fun1);
+    window.registerPort('fun1', port1.toSendPort());
+
+    var fun2 = (message) {
+      Expect.equals(3, message);
+
+      // TODO(vsm): Investigate why this needs to be called asynchronously.
+      window.setTimeout(done, 0);
+    };
+
+    var port2 = new ReceivePortSync();
+    port2.receive(fun2);
+    window.registerPort('fun2', port2.toSendPort());
+
+    new TestIsolate().spawn().then((p) {});
+  });
+}