[DomCrawler] Fix behaviour with <base> tag

Finishes https://github.com/symfony/symfony/issues/12283

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12283, #12143, #12144
| License       | MIT
| Doc PR        | -