unittest step2: bye bye to multiple entrypoints for unittest

tests/isolate/src/APIv2_spawnBrowserNegativeTest.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.
 
 // Negative test to make sure that we are reaching all assertions.
 #library('spawn_tests');
-#import('../../../lib/unittest/unittest_dom.dart');
+#import('../../../lib/unittest/unittest.dart');
+#import('../../../lib/unittest/dom_config.dart');
 #import('dart:dom'); // import added so test.dart can treat this as a webtest.
 #import('dart:isolate');
 
 child() {
   port.receive((msg, reply) => reply.send('re: $msg'));
 }
 
 main() {
+  useDomConfiguration();
   asyncTest('message - reply chain', 1, () {
     ReceivePort port = new ReceivePort();
     port.receive((msg, _) {
       expect(msg).equals('re: hello'); // should be hi, not hello
       port.close();
       callbackDone();
     });
 
     SendPort s = spawnFunction(child);
     s.send('hi', port.toSendPort());
   });
 }