This URL library ends up being a relatively fundamental base library of
the system, as LibCore depends on LibURL.
This change has two main benefits:
* Moving AK back more towards being an agnostic library that can
be used between the kernel and userspace. URL has never really fit
that description - and is not used in the kernel.
* URL _should_ depend on LibUnicode, as it needs punnycode support.
However, it's not really possible to do this inside of AK as it can't
depend on any external library. This change brings us a little closer
to being able to do that, but unfortunately we aren't there quite
yet, as the code generators depend on LibCore.
This isn't included in the base definition of a CSS-wide keyword, but
the CASCADE-4 spec which adds it says:
> The revert CSS-wide keyword rolls back the cascade to the cascaded
value of the earlier origin.
So it is one. While I'm at it, rename `is_builtin()` to match the spec
terminology. It's not used currently, but will be in the next commit.
The `to_string()` for this is modified a little from the original,
because we have to calculate what the layer-count is then, instead of
having it already calculated.
This one is a bit fun because it can be `add(<integer>)` or `auto-add`,
but children have to inherit the computed value not the specified one.
We also have to compute it before computing the font-size, because of
`font-size: math` which will be implemented later.
This saves us from having to manually write these every time we add a
new type of StyleValue:
- bool is_foo() const;
- FooStyleValue const& as_foo() const;
- FooStyleValue& as_foo();
This is a universal value like `initial` and `inherit` and works by
reverting the current value to whatever we had at the start of the
current cascade origin.
The implementation is somewhat inefficient as we make a copy of all
current values at the start of each origin. I'm sure we can come up with
a way to make this faster eventually.
Having one StyleValue for `<number>` and `<integer>` is making user code
more complicated than it needs to be. We know based on the property
being parsed, whether it wants a `<number>` or an `<integer>`, so we
can use separate StyleValue types for these.
Specifically, stop letting NumericStyleValues holding `0` from
pretending to hold a Length. The parser is now smart enough that we
don't have to do this. :^)
Only NumericStyleValue holds integers.
I'm not sure our current distinction between NumericStyleValue holding
an integer or non-integer is useful given it always returns a float.
:thonk:
The Display class already supported all specific values, and now they
will be parsed too. The display property now has a special type
DisplayStyleValue.
