Split out long-running serialization test and add timings to output

tests/compiler/dart2js/serialization/model0_test.dart

Index: tests/compiler/dart2js/serialization/model0_test.dart
diff --git a/tests/compiler/dart2js/serialization/model2_test.dart b/tests/compiler/dart2js/serialization/model0_test.dart
similarity index 78%
copy from tests/compiler/dart2js/serialization/model2_test.dart
copy to tests/compiler/dart2js/serialization/model0_test.dart
index 369e4a13f1e39693e8029b9e4b6ffa74840bcbcc..39245e5cdfbe17a65ded0f4635d1f39353a86794 100644
--- a/tests/compiler/dart2js/serialization/model2_test.dart
+++ b/tests/compiler/dart2js/serialization/model0_test.dart
@@ -2,11 +2,11 @@
 // 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 dart2js.serialization.model2_test;
+library dart2js.serialization.model0_test;
 
 import 'model_test_helper.dart' as test;
 import 'test_data.dart';
 
 main() {
-  test.main(['${TESTS.length ~/ 2}']);
+  test.main(['0', '0']);
 }