This commit on its own has no observable behaviour changes, as we still
only return True or False, but for the next commit, we'll need to be
able to return the Unknown state here, and without this change we'd get
regressions.
The current spec defines this simply as `<ident>`, but does apparently
serialize as lowercase.
Because of this change, we no longer need to care about the deprecated
media types, as they all behave the same as unknown ones.
We still keep an enum around for KnownMediaType, to avoid repeated
string comparisons when evaluating it.
Gets us 2 WPT passes.
A MediaFeature either has a MediaFeatureValue, or a Range, or nothing.
Combining these into a Variant reduces the size from 176 bytes to 128,
and also makes constructing these a little less awkward.
CSS Values 5 now defines a `<boolean-expr[]>` type that is used in place
of the bespoke grammar that previously existed for `@media` and
`@supports` queries. This commit implements some BooleanExpression
types to represent the nodes in a `<boolean-expr[]>`, and reimplements
`@media` and `@supports` queries using this.
The one part of this implementation I'm not convinced on is that the
`evaluate()` methods take a `HTML::Window*`. This is a compromise
because `@media` requires a Window, and `@supports` does not require
anything at all. As more users of `<boolean-expr[]>` get implemented in
the future, it will become clear if this is sufficient, or if we need
to do something smarter.
As a bonus, this actually improves our serialization of media queries!
