constructor(identifierGenerator, reporter, options) {
    super(identifierGenerator, reporter, options);
    this.options = options;
  }
Adds support for spread properties on object literals

https://github.com/sebmarkbage/ecmascript-rest-spread/blob/master/Spec.md

{a, ...b, c, ...d}
=>
$spreadProperties({a}, b, {c}, d)