Produce JS-visible string results as UTF-16 at their source, including
numeric formatting, BigInt and BigFraction formatting, URI encoding,
console formatting, parser errors, regular expression errors, Intl and
Temporal records, LibUnicode locale boundaries, and LibWeb bindings.
Handle fractional radix formatting through the UTF-16 builder view.
The arguments Span (pointer + size = 16 bytes) was always derivable
from the tail array layout: data = values + (total_count - arg_count).
Replace it with a u32 argument_count and derive the span on demand
via arguments_span() / arguments_data() accessors.
Shrinks ExecutionContext from 136 to 120 bytes.
Adds inline implementation for the most common case when `Value` is
already an object.
1.47x improvement on the following benchmark:
```js
const o = {};
for (let i = 0; i < 10_000_000; i++) {
o.a = 1;
o.b = 2;
o.c = 3;
}
```
This is better because:
- Better data locality
- Allocate vector for registers+constants+locals+arguments in one go
instead of allocating two vectors separately
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
Now that the heap has no knowledge about a JavaScript realm and is
purely for managing the memory of the heap, it does not make sense
to name this function to say that it is a non-realm variant.
