DevTools needs rule-level source positions to link applied style
rules back to their source sheets. The parser already tracks token
line and column information, so carry that through qualified rules
and nested declarations when creating CSSRule objects.
Treat a scoped `@import` rule as a scope descriptor while traversing
style-producing rules from imported stylesheets. Imported rules now
inherit an outer scope for unscoped imports and replace it when the
import itself carries scope(...).
Scope resolution was generalized to handle both CSSScopeRule and
CSSImportRule descriptors. Import-scope boundaries are matched using
the stylesheet that parsed the `@import` rule, while normal imported
selectors keep using the imported stylesheet context. This lets
implicit scopes, nested `@scope` rules, :scope, and top-level `&` behave
as the Cascade 6 model requires.
`@scope (a) to (b) {}` applies its contained style rules to elements
that have `a` as a parent, and do not have `a b` as a parent. Both the
`a` and `b` selector lists are optional.
Because it's situational whether a `@scope` will apply to a given
element, we store the ancestor scope on the `MatchingRule`, similar to
`@container`, and then determine during matching whether all the parent
`@scope`s match or not.
The rules for how selectors inside `@scope` are adjusted and interpreted
are a bit confusing. Unlike for other at-rules, nested style rules
inside `@scope` do not get a leading `&` added during parsing. To
support this, `adapt_nested_relative_selector_list()` now takes a flag
for whether its parent is a `@scope` or not.
`@scope` can also contain nested declarations without itself being
nested inside a style rule.
When determining their selectors, nested declarations rules adopt the
`@scope`'s scoping root if it has one, or otherwise fall back to the
parent element of the `<style>` element (not implemented here,) or the
`:root`. These are required to have zero specificity, so we wrap the
selector in `:where()`.
No parsing yet, just CSSContainerRule and the supporting ContainerQuery
class.
CSSContainerRule is unusual in how it matches, because instead of it
either matching or not matching globally, it instead is matched against
a specific element. But also, some at-rules inside it always apply, as
if they were written outside it. This doesn't fit well with how
CSSConditionRule is implemented, and will likely require some rework
later. For now, `condition_matches()` always returns false, and
`for_each_effective_rule()` is overridden to always process those
global at-rules and nothing else.
In a later commit the caches to clear will be stored against a document
so the rule will require still having reference to that document to
clear it.
Also take this opportunity to mark `set_parent_style_sheet` as
`MUST_UPCALL`
Having the dumping code in a separate Dump.cpp meant that it was often
overlooked when the rules gained new features, and also limits dumping
to publicly-accessible information.
This is a bit under-specced, specifically there's no definition of
CSSMarginDescriptors so I've gone with CSSStyleProperties for now. Gets
us 17 WPT subtests.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
