Merge kernel closure conversion into the Dart SDK

pkg/kernel/test/treeshaker_membench.dart

 #!/usr/bin/env dart
 // Copyright (c) 2016, 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 kernel.treeshaker_membench;
 
 import 'package:kernel/kernel.dart';
 import 'package:kernel/transformations/treeshaker.dart';
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:args/args.dart';
 import 'dart:io';
 
 ArgParser argParser = new ArgParser()
-  ..addOption('count', abbr: 'c',
-      help: 'Build N copies of the tree shaker',
-      defaultsTo: '100');
+  ..addOption('count',
+      abbr: 'c', help: 'Build N copies of the tree shaker', defaultsTo: '100');
 
 String usage = """
 Usage: treeshaker_membench [options] FILE.dart
 
 Options:
 ${argParser.usage}
 """;
 
 /// Builds N copies of the tree shaker data structure for the given program.
 /// Pass --print-metrics to the Dart VM to measure the memory use.
@@ skipping 26 matching lines @@
 
   print('$copyCount copies built');
 
   if (args.contains('-v')) {
     // Use of the list for something to avoid premature GC.
     for (var treeShaker in keepAlive) {
       treeShaker.getClassRetention(hierarchy.rootClass);
     }
   }
 }