add tool to get breakdown of deferred libraries by size

bin/deferred_library_check.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.
 
 /// A command-line tool that verifies that deferred libraries split the code as
 /// expected.
 /// This tool checks that the output from dart2js meets a given specification,
 /// given in a YAML file. The format of the YAML file is:
 ///
 ///     main:
@@ skipping 18 matching lines @@
 /// contained in that part. Any package that is not explicitly listed is
 /// expected to be in the main part. For instance, in the example YAML above
 /// the part named "baz" is expected to contain the packages "baz" and "quux".
 ///
 /// The names for parts given in the specification YAML file (besides "main")
 /// are arbitrary and just used for reporting when the output does not meet the
 /// specification.
 library dart2js_info.bin.deferred_library_check;
 
 import 'dart:async';
-import 'dart:convert';
 import 'dart:io';
 
-import 'package:dart2js_info/info.dart';
 import 'package:dart2js_info/deferred_library_check.dart';
+import 'package:dart2js_info/src/util.dart';
 import 'package:yaml/yaml.dart';
 
 Future main(List<String> args) async {
   if (args.length < 2) {
     usage();
     exit(1);
   }
   var info = await infoFromFile(args[0]);
   var manifest = await manifestFromFile(args[1]);
 
   var failures = checkDeferredLibraryManifest(info, manifest);
   failures.forEach(print);
   if (failures.isNotEmpty) exitCode = 1;
 }
 
-Future<AllInfo> infoFromFile(String fileName) async {
-  var file = await new File(fileName).readAsString();
-  return new AllInfoJsonCodec().decode(JSON.decode(file));
-}
-
 Future manifestFromFile(String fileName) async {
   var file = await new File(fileName).readAsString();
   return loadYaml(file);
 }
 
 void usage() {
   print('''
 usage: dart2js_info_deferred_library_check dump.info.json manifest.yaml''');
 }