Move the remaining CSSStyleDeclaration property-name APIs to
Utf16FlyString. This lets CSSOM binding and generated accessor code
pass JS property names without first constructing FlyString values.
Keep internal custom-property and descriptor storage unchanged for now.
Those remaining FlyString conversions are at storage boundaries that
will be migrated in follow-up commits.
Change get_property_value() to take a Utf16FlyString so generated CSS
property accessors can pass their JS property names through without
constructing FlyString instances first.
Keep the existing internal descriptor and custom-property storage shape
for now, and convert at those boundaries while the remaining CSS
property APIs are migrated separately.
Remove the visit_edges hook from CSS::StyleValue and stop asking CSS
properties, descriptors, computed values, and layout nodes to trace
through their style values.
Style values are refcounted data objects, so they should not be part of
the GC graph. Keeping this cleanup separate makes the later layout tree
ownership change smaller and easier to review.
Some at-rules (i.e. `@function`) require us to support custom
descriptors (e.g. `--foo`).
We do this by adding `DescriptorID::Custom` and using a new
`DescriptorNameAndID` class in a bunch of places where we previously
just used `DescriptorID`
By making use of the WEB_PLATFORM_OBJECT macro we can remove
the boilerplate of needing to add this override for every
serializable platform object so that we can check whether they
are exposed or not.
StylePropertyMap only ever works with style properties - never
descriptors. Switching `has_property()` and `get_property_style_value()`
to taking PropertyNameAndID skips some duplicate work.
This isn't part of the CSSOM API directly, but will be used by
StylePropertyMapReadOnly.has() to avoid doing the work to serialize a
string version of the property's value, just to throw it away again.
This reverts 0e3487b9ab.
Back when I made that change, I thought we could make our StyleValue
classes match the typed-om definitions directly. However, they have
different requirements. Typed-om types need to be mutable and GCed,
whereas StyleValues are immutable and ideally wouldn't require a JS VM.
While I was already making such a cataclysmic change, I've moved it into
the StyleValues directory, because it *not* being there has bothered me
for a long time. 😅
I was wrong when I added those notes before about this being impossible,
it's *very* possible, for example with the `@page margin` descriptor.
However, until we have a large number of these shorthands and not just a
single example, we can get away with hard-coding support for it.
This holds the boilerplate that's needed by any CSSStyleDeclaration
subclass that holds Descriptors. CSSFontFaceDescriptors now only has to
worry about initialization and its own exposed properties.
