This is a monster patch that turns all EventTargets into GC-allocated
PlatformObjects. Their C++ wrapper classes are removed, and the LibJS
garbage collector is now responsible for their lifetimes.
There's a fair amount of hacks and band-aids in this patch, and we'll
have a lot of cleanup to do after this.
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.
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! :^)
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.
