Split serialization tests further

tests/compiler/dart2js/serialization/model_1_test.dart

Index: tests/compiler/dart2js/serialization/model_1_test.dart
diff --git a/tests/compiler/dart2js/serialization/model1_test.dart b/tests/compiler/dart2js/serialization/model_1_test.dart
similarity index 69%
copy from tests/compiler/dart2js/serialization/model1_test.dart
copy to tests/compiler/dart2js/serialization/model_1_test.dart
index 414ef5c9433abc821f4e86c82c5c2980aaa27ef9..e74bd171aa53c353967828f823636053b6d2d8b1 100644
--- a/tests/compiler/dart2js/serialization/model1_test.dart
+++ b/tests/compiler/dart2js/serialization/model_1_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.model1_test;
+library dart2js.serialization.model_1_test;
 
 import 'model_test_helper.dart' as test;
-import 'test_data.dart';
+import 'test_helper.dart';
 
 main() {
-  test.main(['1', '${TESTS.length ~/ 2}']);
+  test.main(testSkipped(1, test.SKIP_COUNT));
 }