Support asynchronous main methods.

lib/src/runner/vm/isolate_listener.dart

 // Copyright (c) 2015, 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 test.runner.vm.isolate_listener;
 
 import 'dart:isolate';
 import 'dart:async';
 
 import '../../backend/declarer.dart';
@@ skipping 33 matching lines @@
     if (main is! Function) {
       _sendLoadException(sendPort, "Top-level main getter is not a function.");
       return;
     } else if (main is! AsyncFunction) {
       _sendLoadException(
           sendPort, "Top-level main() function takes arguments.");
       return;
     }
 
     var declarer = new Declarer();
-    try {
-      runZoned(main, zoneValues: {#test.declarer: declarer});
-    } catch (error, stackTrace) {
+    runZoned(() => new Future.sync(main), zoneValues: {
+      #test.declarer: declarer
+    }).then((_) {
+      var suite = new Suite(declarer.tests, metadata: metadata)
+          .forPlatform(TestPlatform.vm, os: currentOS);
+      new IsolateListener._(suite)._listen(sendPort);
+    }, onError: (error, stackTrace) {
       sendPort.send({
         "type": "error",
         "error": RemoteException.serialize(error, stackTrace)
       });
-      return;
-    }
-
-    var suite = new Suite(declarer.tests, metadata: metadata)
-        .forPlatform(TestPlatform.vm, os: currentOS);
-    new IsolateListener._(suite)._listen(sendPort);
+    });
   }
 
   /// Sends a message over [sendPort] indicating that the tests failed to load.
   ///
   /// [message] should describe the failure.
   static void _sendLoadException(SendPort sendPort, String message) {
     sendPort.send({"type": "loadException", "message": message});
   }
 
   IsolateListener._(this._suite);
@@ skipping 51 matching lines @@
             asyncError.error, asyncError.stackTrace)
       });
     });
 
     liveTest.onPrint.listen((line) =>
         sendPort.send({"type": "print", "line": line}));
 
     liveTest.run().then((_) => sendPort.send({"type": "complete"}));
   }
 }