Remove the `swf_version` parameter from `Activation` constructors,
because this was incorrectly using the global or root SWF version
most times.
Instead, grab the SWF version for the activation directly from the
base clip.
Instead of storing shared pointers to `Avm1ConstructorRegistry` in
`MovieLibrary`, access the `PropertyMap` directly, without an extra
abstraction.
Also, move the constructor registries to `Avm1`, for better
encapsulation.
This might create templatized functions leading to unnecessary code bloat.
So instead use just `Value<'gc>` parameters and add `.into()` in callers
where needed.
This allows for reduced boilerplate when defining native methods,
properties, and constants (but not values depending on other runtime
values, like built-ins objects and prototypes).
Also remove ScriptObject::force_set_function (replaced by DeclKind::Method)
* Built-in constructors now return the newly constructed object,
which will be used as `this`. This allows for constructors such
as `new Object` which can return differing types.
* Adjust `FunctionObject::constructor` to take both a constructor
and a function. Add `constructor_to_fn!` macro to turn most
simple native constructors into a function that discards the
return value.
* Change `TObject::construct` to return `Value` instead of `Object`.
This is necessary for constructors that return primitive values.
Notably, all of the `Avm1` "run stack frame" functions can no longer take a self parameter as the update context they will be getting also has that same parameter. Ergo, they're associated functions that get the moral equivalent of self from the update context.
This also introduces a new `Activation::from_stub` which creates a stub frame that runs everything on the main movie in layer 0. This significantly reduces boilerplate code elsewhere in the project.
The process of constructing an `Activation` now involves calling `UpdateContext.reborrow`, which "sheds" a lifetime by copying all of the borrows into a new "owned" context with that lifetime.
Likewise, to call out to functions that don't need an `Activation`, just borrow the context out of the current activation. You can also construct child-frame activations by reborrowing the parent activation's context.