Prepare to use invalidation set for adding/removing RuleSets.
Currently, we sometimes use StyleSheetInvalidationAnalysis to be smart
about recalculating affected element when adding/removing a stylesheet.
The plan is to start using the StyleInvalidator to trigger style
recalculations When adding/removing stylesheets. We will then use the
invalidation sets from the stylesheet RuleSet and schedule them on
elements in the stylesheet's document or shadow tree.
We fall back to a full recalc for the document / shadow tree for if we
find selectors which don't have simple selectors for which we have an
invalidation set we can use. This is similar to what we do with the
universalSiblingInvalidationSet for DOM mutations.
This first implementation supports id, class, attribute, and type
selectors in the rightmost compound[1]. We could later support to use
invalidation sets for universal pseudo class rules like ":hover".
The invalidations are to be scheduled for elements in the same
TreeScope as the stylesheet, including the host element.
Rules which are boundary crossing have their features collected in
ScopedStyleResolver::addTreeBoundaryCrossingRules() and not in their
respective stylesheet's RuleSet. We fall back to full style recalc
for rules containing ::content, ::shadow, and /deep/. ::slotted rules
are currently also collected on the ScopedStyleResolver, but in order
to avoid full recalcs, we do LocalStyleChange on slot-distributed
elements for RuleSet invalidations when there are ::slotted rules in
the RuleSet.
As mentioned earlier we will schedule invalidations on the host element
as well, which means we will schedule the invalidation set for ".a" for
":host(.a)". :host-context() do also support RuleSet invalidation as
long as there are features in addition to the ones inside the
:host-context() pseudo.
As for sibling invalidations on DOM mutations, negated selectors like
":not(.a)" are considered universal.
This CL is split out of [2]. The next step is to land the invalidation
code in StyleEngine from the same CL.
[1] Even though we don't have invalidation sets for tag names, we can
check the presence of rules in the tag name hash map for the RuleSet.
This means "body *" will cause a full recalc, but "body" won't. Also
note that "div.enabled" will cause every div element to be invalidated
because the rule would end up in the class rule hashmap.
[2] https://codereview.chromium.org/1913833002/
R=ericwilligers@chromium.org
BUG=567021
Review-Url: https://codereview.chromium.org/2326033002
Cr-Commit-Position: refs/heads/master@{#419704}
4 files changed
