Fix ActiveRecord `subclass_from_attrs` when eager_load is false.
It cannot find subclass because all classes are loaded automatically
when it needs.
Merge pull request #9497 from route/subclass_from_attrs

Fix ActiveRecord `subclass_from_attrs` when eager_load is false.

Conflicts:
	activerecord/CHANGELOG.md
Avoid short-circuit return
Make sure options is a hash