[Serializer] Fix CS
minor #12127 [WIP] minor [Serializer] Fix CS (dunglas)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[WIP] minor [Serializer] Fix CS

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

* Reverts CS breaks introduced by #12102 found by @stof and @xabbuh.
* Fix CS of `PropertyNormalizer` (missed in last commit)

Commits
-------

dffa3e4 [Serializer] Fix CS