simplifying method_missing functionality with Proxy

gistfile1.js

var root = (function(){ return this; })();

function ProxyClass() {
  if (this === root) throw Error();
  var instance = this;
  return Proxy.create({
    get: function(receiver, name) {
      console.log('get', name);
      return instance[name] || (instance._get && instance._get(name, receiver)) || undefined;
    },
    set: function(receiver, name, value) {
      console.log('set', name, value);
      if (instance._set) {
        return instance._set(name, value, receiver) !== false;
      }

      instance[name] = value;
      return true;
    },
    has: function(name) {
      console.log('has', name);
      return name in instance || (instance._has && instance._has(name));
    },
    hasOwn: function(name) {
      console.log('hasOwn', name);
      return instance.hasOwnProperty(name) || (instance._hasOwn && instance._hasOwn(name, value, receiver));
    }
  }, instance);
}

ProxyClass.prototype = {
  _get: function(name) {
    console.log('class get');
    return this[name];
  },
  _set: function(name, value) {
    console.log('class set');
    this[name] = value;
  },
  _has: function(name) {
    console.log('class has');
    return name in this;
  },
  _hasOwn: function(name) {
    console.log('class hasOwn');
    return Object.hasOwnProperty(name);
  }
};

var proxy = ProxyClass();

console.log('first', proxy.first);

proxy.first = 123;

console.log('first2', proxy.first);

console.log('toString', proxy.toString());
console.log('proxy instanceof ProxyClass', proxy instanceof ProxyClass);
console.log(Object.prototype.toString.call(proxy));

function InheritProxy() {
  return ProxyClass.apply(this, arguments);
}

InheritProxy.prototype = Object.create(ProxyClass.prototype);

InheritProxy.prototype._get = function(name) {
  console.log('subclass get');
  return this[name];
};

var subproxy = new InheritProxy();

console.log('sfirst', subproxy.first);

subproxy.first = 123;

console.log('sfirst2', subproxy.first);

console.log('toString', subproxy.toString());

console.log('subproxy instanceof InheritProxy', subproxy instanceof InheritProxy);
console.log('subproxy instanceof ProxyClass', subproxy instanceof ProxyClass);
console.log(Object.prototype.toString.call(subproxy));