text: //// [fatarrowfunctionsInFunctionParameterDefaults.ts]
  function fn(x = () => this, y = x()) {
  
      // should be 4
      return y;
  
  }
  
  fn.call(4); // Should be 4
  
  
  //// [fatarrowfunctionsInFunctionParameterDefaults.js]
  function fn(x, y) {
      var _this = this;
      if (x === void 0) { x = function () { return _this; }; }
      if (y === void 0) { y = x(); }
      // should be 4
      return y;
  }
  fn.call(4); // Should be 4
  