Convert between Dart and JavaScript SerializedScriptValues on postMessage.

tests/html/postmessage_structured_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('postmessage_js_test');
+#import('../../pkg/unittest/unittest.dart');
+#import('../../pkg/unittest/html_config.dart');
+#import('dart:html');
+
+injectSource(code) {
+  final script = new ScriptElement();
+  script.type = 'text/javascript';
+  script.innerHTML = code;
+  document.body.nodes.add(script);
+}
+
+
+main() {
+  useHtmlConfiguration();
+
+  test('js-to-dart-postmessage', () {
+      // Pass an object literal from JavaScript. It should be seen as a Dart
+      // Map.
+
+      final JS_CODE = """
+        window.postMessage({eggs: 3, recipient: 33}, '*');
+        """;
+      var callback;
+      var onSuccess = expectAsync1((e) {
+          window.on.message.remove(callback);
+        });
+      callback = (e) {

[vsm, 2012/10/04 16:03:35]

I think you want to guardAsync this code.

+        var data = e.data;
+        if (data is String) return;    // Messages from unit test protocol.
+        expect(data is Map);
+        expect(data['eggs'], equals(3));
+        onSuccess(e);
+      };
+      window.on.message.add(callback);
+      injectSource(JS_CODE);
+    });

[vsm, 2012/10/04 16:03:35]

Are cycles supported in the data?  If so, perhaps test?

+
+
+  test('dart-to-js-to-dart-postmessage', () {
+      // Pass dictionaries between Dart and JavaScript.
+
+      final JS_CODE = """
+        window.addEventListener('message', handler);
+        function handler(e) {
+          var data = e.data;
+          if (typeof data == 'string') return;
+          if (data.recipient != 'JS') return
+          var response = {recipient: 'DART'};
+          response[data['curry']] = 50;
+          window.removeEventListener('message', handler);
+          window.postMessage(response, '*');
+        }
+        """;
+      var callback;
+      var onSuccess = expectAsync1((e) {
+          window.on.message.remove(callback);
+        });
+      callback = (e) {

[vsm, 2012/10/04 16:03:35]

ditto on guardAsync

+        var data = e.data;
+        if (data is String) return;    // Messages from unit test protocol.
+        expect(data is Map);
+        if (data['recipient'] != 'DART') return;  // Hearing the sent message.
+        expect(data['peas'], equals(50));
+        onSuccess(e);
+      };
+      window.on.message.add(callback);
+      injectSource(JS_CODE);
+      window.postMessage({'recipient': 'JS', 'curry': 'peas'}, '*');
+    });
+}