when save object A,B,C B/C extend A

**Steps to Reproduce**
example ：
when save object class A,B,C B/C extend A 。
if register typeadapter with sort: A-adapter,B-adapter,C-adapter

when save B, will use A-adapter，it will lose properties of B。

reason: match adapter use value is T,
class ResolvedAdapter {
final TypeAdapter adapter;
final int typeId;

ResolvedAdapter(this.adapter, this.typeId);

bool matches(dynamic value) => value is T; //here value is T, B and C alse subclass of A,so return true
}