Fix return type of DOMXPath::query

[staabm]

This can also return namespace nodes, which are not a child class of DOMNode.

analog vimeo/psalm#10443

[phpstan-bot]

This pull request has been marked as ready for review.

[ondrejmirtes]

Please show an example on 3v4l.org with examples of using this method and the cases where it returns different objects as stated in this PR. I'm worried of typical problems like that in 99 % of cases this is going to return what's already stated in the file, and this change is going to report these 99 % of cases for the sake of correctness for the 1 %.

[staabm]

https://3v4l.org/GpOJA

[ondrejmirtes]

So only a query that starts with namespace is going to return that?

[nielsdos]

So only a query that starts with namespace is going to return that?

Only queries that explicitly request namespace nodes return that.

[ondrejmirtes]

Yeah so this PR isn't really worth it in the current form.