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 line 143 of `PropertyNormalizer`.