babel class properties

https://babeljs.io/docs/en/babel-plugin-proposal-class-properties

  class Bork {
    static a = 'foo';
    static b;

    x = 'bar';
    y;
  }

becomes...

var Bork = function Bork() {
  babelHelpers.classCallCheck(this, Bork);
  Object.defineProperty(this, "x", {
    configurable: true,
    enumerable: true,
    writable: true,
    value: 'bar'
  });
  Object.defineProperty(this, "y", {
    configurable: true,
    enumerable: true,
    writable: true,
    value: void 0
  });
};

Object.defineProperty(Bork, "a", {
  configurable: true,
  enumerable: true,
  writable: true,
  value: 'foo'
});
Object.defineProperty(Bork, "b", {
  configurable: true,
  enumerable: true,
  writable: true,
  value: void 0
});