add a JsonInfoCodec class

bin/inference/print_summary.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.
 
 /// Utility to display statistics about "sends" as a table on the command line.
 library compiler.tool.stats.print_summary;
 
 import 'dart:io';
 import 'dart:convert';
 import 'package:dart2js_info/info.dart';
 import 'package:dart2js_info/src/table.dart';
 
 main(args) {
   var file = args.length > 0 ? args[0] : 'out.js.info.json';
   var json = JSON.decode(new File(file).readAsStringSync());
-  var results = new AllInfo.fromJson(json);
+  var results = new AllInfoJsonCodec().decode(json);
   print(formatAsTable(results));
 }
 
 /// Formats [results] as a table.
 String formatAsTable(AllInfo all) {
   var visitor = new _Counter();
   all.accept(visitor);
   var table = new Table();
   table.declareColumn('bundle');
 
@@ skipping 60 matching lines @@
     currentBundleTotals.addFrom(measurements);
   }
 }
 
 const _groupColors = const [_YELLOW_COLOR, _NO_COLOR];
 
 const _NO_COLOR = "\x1b[0m";
 const _GREEN_COLOR = "\x1b[32m";
 const _YELLOW_COLOR = "\x1b[33m";
 const _WHITE_COLOR = "\x1b[37m";