[php-src] PR #25240: Fix combinators after a compound-leading selector-taking pseudo-class

Pull Request: https://github.com/php/php-src/pull/25240 Author: phcorp When :is(), :where(), :not(), :has() or :nth-child(An+B of S) starts a compound selector, the combinator after it only checks the nearest element. A descendant combinator acts like >, and ~ acts like +: ```php $d = Dom\HTMLDocument::createFromString('<!doctype html><ul><li>a<ol><li>b</li></ol></li></ul>'); count($d->querySelectorAll(':is(ul) li')); // 1, expected 2 count($d->querySelectorAll('*:is(ul) li')); // 2 ``` Reported upstream as lexbor/lexbor#436 and fixed there by lexbor/lexbor@f6c1d06. Dom\ uses its own adapted copy of the matcher, so updating the bundled lexbor doesn't pick up the fix. This ports the same change into ext/dom/lexbor/lexbor/selectors-adapted/selectors.c: when a nested selector rejects a candidate, keep walking the descendant/subsequent-sibling combinator (and the child combinator in forward mode) before backtracking to another entry. lexbor436.phpt covers every selector from the upstream issue. It fails on PHP-8.4 HEAD (8 of 8 cases) and passes with this change. The ext/dom suite passes. The patch applies cleanly to PHP-8.5 and master.