Objects should get the GlobalObject from themselves instead. However,
it's not yet available during construction so this only switches code
that happens after construction.
To support multiple global objects, Interpreter needs to stop holding
on to "the" global object and let each object graph own their global.
As these parameter-less overloads don't change the value's type and
just assume Type::Number, naming them as_i32() and as_size_t() is more
appropriate.
Passing a Heap& to it only to then call interpreter() on that is weird.
Let's just give it the Interpreter& directly, like some of the other
to_something() functions.
JS::Value already has the empty state ({} or Value() gives you one.)
Use this instead of wrapping Value in Optional in some places.
I've also added Value::value_or(Value) so you can easily provide a
fallback value when one is not present.
value and bound arguments
This allows Function objects produced by Function.prototype.bind, as well
as arrow functions to track their |this| values and bound arguments.
Everyone who constructs an Object must now pass a prototype object when
applicable. There's still a fair amount of code that passes something
fetched from the Interpreter, but this brings us closer to being able
to detach prototypes from Interpreter eventually.
