Summary:
This diff adds fields for ObjC properties to the type environment. For example,
```
property type fieldname;
```
when the property name is "fieldname", this diff adds a struct field of the same name.
The missing type information were problematic in inferbo, since its semantics depend on types.
Reviewed By: ezgicicek
Differential Revision: D28421998
fbshipit-source-id: e24059846