test renaming overhaul: step 4 client tests

tests/dom/messageevent_test.dart

 #library('SerializedScriptValueTest');
-#import('../../../../lib/unittest/unittest.dart');
-#import('../../../../lib/unittest/dom_config.dart');
+#import('../../lib/unittest/unittest.dart');
+#import('../../lib/unittest/dom_config.dart');
 #import('dart:dom');
 
 main() {
   useDomConfiguration();
 
   test('MessageEvent.initMessageEvent', () {
       final event = document.createEvent('MessageEvent');
       event.initMessageEvent('type', false, true, 'data', 'origin', 'lastEventId', window, []);
       expect(event.type).equals('type');
       expect(event.bubbles).equals(false);
       expect(event.cancelable).equals(true);
       expect(event.data).equals('data');
       expect(event.origin).equals('origin');
       expect(event.lastEventId).equals('lastEventId');
       expect(event.source).same(window);
       // TODO(antonm): accessing ports is not supported yet.
   });
 }