put Map<String,dynamic>,but get result is Map<dynamic,dynamic>

**Code sample**
If read directly without restarting the application after depositing, it is . If the application is restarted, it will be wrong.

```
Map map = {"ss":2,"s":"ss"};
var box = Hive.box(commonBox);
box.put('map', map);
```
then
```
var box = Hive.box(commonBox);
var map = box.get('map', map);
debugPrint('==map=${map.runtimeType}');
// flutter: ==map=_Map

```

**Version**
- Platform: iOS, Android, Mac, Windows, Linux, Web
- Flutter version: [e.g. 1.5.4]
- Hive version: [e.g. 0.5.0]

Start with the supplied Hive.box, put, and get sample, comparing the map type before and after restarting the application. Trace Hive's map serialization and deserialization behavior; done means retrieving the stored Map preserves the expected key type after restart, with the behavior verified on the reported platforms.

Written by the indexing model from the issue text.