Previously, some StyleValues created a large number of intermediate
strings during serialization. Passing a StringBUilder into the
serialization function allows us to avoid a large number of these
unnecessary allocations.
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. 😅
This parses `anchor-size(..)` functions in CSS, but does not yet result
in a useful `Size`: we need style & layout interleaving similar to
container queries for this, since the resulting value depends on layout
results.
Not supported yet: `anchor-size()` appearing inside a `calc()` node.
Adds 4280 WPT subtest passes in `css/css-anchor-position`.
