LibWeb: Route presentational hints through the CSS cascade

Previously, presentational hints bypassed the regular cascade pipeline
and wrote directly into `CascadedProperties` under
`CascadeOrigin::Author`. That meant `var()` substitution and the
invalid-at-computed-value-time fallback had to be duplicated in a
separate per-element pass, which in practice missed the IACVT step and
could leave a `GuaranteedInvalidStyleValue` in the cascaded
properties. This caused a crash in downstream code that assumed the
value had been resolved.

This introduces an `AuthorPresentationalHint` cascade origin and feeds
them through the cascade as normal declarations. This means that
`var()` resolution now happens in only one place.
This commit is contained in:
Tim Ledbetter
2026-04-30 10:44:26 +01:00
committed by Sam Atkins
parent 297b1af9bf
commit d1fc4b4234
Notes: github-actions[bot] 2026-04-30 18:51:41 +00:00
67 changed files with 316 additions and 374 deletions

View File

@@ -6,7 +6,6 @@
#include <LibWeb/Bindings/HTMLTableCaptionElement.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/CascadedProperties.h>
#include <LibWeb/CSS/ComputedProperties.h>
#include <LibWeb/CSS/StyleValues/KeywordStyleValue.h>
#include <LibWeb/HTML/HTMLTableCaptionElement.h>
@@ -37,13 +36,13 @@ bool HTMLTableCaptionElement::is_presentational_hint(FlyString const& name) cons
}
// https://html.spec.whatwg.org/multipage/rendering.html#tables-2
void HTMLTableCaptionElement::apply_presentational_hints(GC::Ref<CSS::CascadedProperties> cascaded_properties) const
void HTMLTableCaptionElement::apply_presentational_hints(Vector<CSS::StyleProperty>& properties) const
{
HTMLElement::apply_presentational_hints(cascaded_properties);
HTMLElement::apply_presentational_hints(properties);
for_each_attribute([&](auto& name, auto& value) {
if (name == HTML::AttributeNames::align) {
if (value == "bottom"sv)
cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::CaptionSide, CSS::KeywordStyleValue::create(CSS::Keyword::Bottom));
properties.append({ .property_id = CSS::PropertyID::CaptionSide, .value = CSS::KeywordStyleValue::create(CSS::Keyword::Bottom) });
}
});
}