add tool to verify dependency information

lib/info.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.
 
 /// Data produced by dart2js when run with the `--dump-info` flag.
 library dart2js_info.info;
 
 import 'src/measurements.dart';
 export 'src/measurements.dart';
 
@@ skipping 132 matching lines @@
 
   /// Minor version indicating non-breaking changes in the format. A change in
   /// this version number means that the json parsing in this library from a
   /// previous will continue to work after the change. This is typically
   /// increased when adding new entries to the file format.
   // Note: the dump-info.viewer app was written using a json parser version 3.2.
   final int minorVersion = 6;
 
   AllInfo();
 
-  static AllInfo parseFromJson(Map map) => new _ParseHelper().parseAll(map);
+  factory AllInfo.fromJson(Map json) => new _ParseHelper().parseAll(json);

[Siggi Cherem (dart-lang), 2015/10/14 23:37:02]

since this is a breaking change, we might need to change the version to 0.2.0.

FWIW - I was hoping we remove it entirely once we split the serialization to be
outside of the info classes
(https://github.com/dart-lang/dart2js_info/issues/4), then all to/from json is
detached and we can support different encodings without changing the info API.

[Harry Terkelsen, 2015/10/15 00:13:55]

I added a TODO for this. Let's go with 0.2.0-dev and then roll when we have an
InfoCodec

 
   Map _listAsJsonMap(List<Info> list) {
     var map = <String, Map>{};
     for (var info in list) {
       map['${info.id}'] = info.toJson();
     }
     return map;
   }
 
   Map _extractHoldingInfo() {
@@ skipping 686 matching lines @@
   }
 
   visitField(FieldInfo info) {
     info.closures.forEach(visitFunction);
   }
 
   visitFunction(FunctionInfo info) {
     info.closures.forEach(visitFunction);
   }
 }