Both of these are supposed to be set when the CSSRule is created. The
spec is silent on setting it when a CSSRule is added to a parent. So,
this is a bit ad-hoc.
The parent rule gets set whenever a rule is added to a new parent. The
parent stylesheet gets set whenever the rule or one of its ancestors is
added to a different stylesheet. There may be some nuance there that
I'm missing, but I'm sure we'll find out quickly once we have WPT
running!
The spec is a little bizarre here. One caller of this
(`CSSStyleSheet::insert_rule()`) wants to give it a parsed CSSRule, but
the spec itself wants it to take a string. (As will be used by
`CSSGroupingRule::insert_rule()`) Using a Variant isn't pretty but it's
the best solution I've come to - having two overloads was worse, whether
one called the other or they just duplicated the logic. This seems the
least bad.
We already had the CSSRule::Type enum, but the values were not aligned
with the CSSOM spec. This patch takes care of that, and then exposes
the type of a CSSRule to JavaScript via the "type" attribute.
https://www.w3.org/TR/cssom/ is the more permanent home of the CSSOM
specification's latest version, and is up to date with the draft spec.
Also, https://drafts.csswg.org/ has been down multiple times recently
which made looking things up a pain.
We now evaluate the conditions of `@media` rules at the same point in
the HTML event loop as evaluation of `MediaQueryList`s. This is not
strictly to spec, but since the spec doesn't actually say when to do
this, it seems to make the most sense. In any case, it works! :^)
The main thing missing is that we don't serialize the supports clause,
but for actually using a `@supports (something: cool) {}` rule in CSS,
it works!
The logic is handled by `CSSGroupingRule` and `CSSConditionRule`, so
`CSSMediaRule` only has to report if its condition matches.
Right now, that condition is always false because we do not evaluate the
media query.
This patch makes both of these classes inherit from RefCounted and
Bindings::Wrappable, plus some minimal rejigging to allow us to keep
using them internally while also exposing them to web content.
