Node.cpp currently knows too much about selector invalidation metadata
when deciding whether subtree mutations can affect :has() selectors.
Pull that logic into CSS/Invalidation/HasMutationFeatureCollector so DOM
mutation code can ask a focused helper instead of inspecting
StyleInvalidationData directly.
This is a behavior-preserving extraction. It keeps the existing
conservative fallbacks for featureless subtree-sensitive selectors and
still uses the existing element property matching helper for
pseudo-class metadata.
