Implement `This` for `JsBox<...>`?

[ErichDonGubler]

JsBox<...> appears to implement Object, and Managed. Is there a reason that it doesn't also implement This also? The lack of This implementation currently makes it impossible to have a MethodContext<'_, JsBox<...>>, which is something that was previously possible with declare_type! { ... }.

[kjvalencik]

There's no reason it couldn't but it would not provide value. declare_type is not implemented for the Node-API backend and will not be (it is not very ergonomic and is unsound when used with workers).

The current recommendation is to use JsBox and some glue code in JavaScript to create classes. See this example: https://github.com/neon-bindings/examples/blob/main/examples/async-sqlite/index.js

The goal is to addon classes later with a proc macro design.

neon-bindings/rfcs#43
#745