When @media rules change match state, avoid treating that as a
whole-document stylesheet change. Record the rules under the query
that became effective or ineffective, build the normal stylesheet
invalidation set from those rules, and invalidate only matching
elements. Keep broad invalidation for rule kinds whose effects are not
selector-targetable.
Preserve cascade-wide fallout by reusing stylesheet-change shadow
effect analysis for broad invalidations inside shadow roots. This keeps
:host and slotted content current when active rules in the same shadow
scope can match there.
Also report an imported stylesheet's owner rule when the imported
sheet's own media gate changes. Layered @import rules can affect layer
ordering even when the imported sheet contributes no rules, so they
need the same broad invalidation treatment as other cascade-wide rules.
Add viewport resize coverage for media query breakpoints, broad
shadow-root media invalidation, and empty layered imports whose media
gate changes layer order.
Document.cpp still handled CSS fallout from stylesheet media query match
changes directly. Move active stylesheet evaluation, rule-cache
invalidation, shadow-root fallout, and slot propagation into the CSS
invalidation helper.
Document continues to decide when media queries should be evaluated.
The helper now owns the style invalidation consequences when stylesheet
media queries change match state.
