Split StyleCache's rule matching data from its invalidation metadata.
Allow callers to build either payload independently. Style invalidation
queries no longer force a full rule cache rebuild, and rule matching
no longer builds invalidation metadata as a side effect.
Previously, callers often treated an absent rule cache as proof that no
style invalidation metadata existed. That made some invalidation paths
do nothing until something else had populated the rule cache first.
Build invalidation data before reading it instead, so these paths use
the metadata whenever stylesheet rules require it.
Rebaseline style invalidation counter expectations for the new lazy
build points. Flush setup style work in the structural :has() feature
filter test before measuring each mutation, so the recomputation
counters describe the mutation itself instead of leftover setup work.
Separate MediaQueryList change reporting from stylesheet media rule
invalidation. Creating matchMedia() objects evaluates their own baseline
state, but should not make the next style update walk all active
stylesheets when the media environment has not changed.
This avoids continuous stylesheet media query reevaluation during
YouTube video playback, where repeated matchMedia() creation can make
style flushes do unnecessary work.
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.
