Split serialization tests further

tests/compiler/dart2js/serialization/model_test_helper.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 dart2js.serialization_model_test;
 
 import 'dart:async';
 import 'dart:io';
 import 'package:async_helper/async_helper.dart';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/closure.dart';
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/deferred_load.dart';
 import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/filenames.dart';
 import 'package:compiler/src/js_backend/js_backend.dart';
 import 'package:compiler/src/serialization/equivalence.dart';
 import 'package:compiler/src/tree/nodes.dart';
 import 'package:compiler/src/universe/class_set.dart';
 import '../memory_compiler.dart';
 import 'helper.dart';
 import 'test_data.dart';
 import 'test_helper.dart';
 
+/// Number of tests that are not part of the automatic test grouping.
+int SKIP_COUNT = 2;
+
+/// Number of groups that the [TESTS] are split into.
+int SPLIT_COUNT = 4;
+
 main(List<String> args) {
   asyncTest(() async {
     Arguments arguments = new Arguments.from(args);
     SerializedData serializedData =
         await serializeDartCore(arguments: arguments);
     if (arguments.filename != null) {
       Uri entryPoint = Uri.base.resolve(nativeToUriPath(arguments.filename));
       SerializationResult result = await measure(
           '${entryPoint}', 'serialize', () {
         return serialize(
@@ skipping 324 matching lines @@
   OutputUnit outputUnit2 =
       compiler2.deferredLoadTask.outputUnitForElement(element2);
   check(outputUnit1, outputUnit2,
       'OutputUnit.isMainOutput for $element1 vs $element2',
       outputUnit1.isMainOutput, outputUnit2.isMainOutput);
   checkSetEquivalence(outputUnit1, outputUnit2,
       'OutputUnit.imports for $element1 vs $element2',
       outputUnit1.imports, outputUnit2.imports,
       (a, b) => areElementsEquivalent(a.declaration, b.declaration));
 }