Ability to have property accessors for native objects

[jugglingcats]

It would be nice to be able to define first class properties with native objects. Psuedo-code:

declare_types! {

    /// JS class wrapping Employee records.
    pub class JsEmployee for Employee {

        property name {
            get(call) {
               // return the value
            }
            set(call) {
               // set the value
            }
        }
    }
};

There seems to be (or have been) a SetAccessor method in the v8 or NaN API, but hard to find good references to it!

[kjvalencik]

declare_types have been deprecated. This feature would need to be part of classes 2.0.

neon-bindings/rfcs#43