Inheritance using Object.create

I was going through some links to find out what Object.create functionality has and how does it differs when it comes to create using new as constructor. So I came across this link:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create

This link has a basic example which explains inheritance using Object.create(). Here is the code

// Shape - superclass
function Shape() {
  this.x = 0;
  this.y = 0;
}

// superclass method
Shape.prototype.move = function(x, y) {
  this.x += x;
  this.y += y;
  console.info('Shape moved.');
};

// Rectangle - subclass
function Rectangle() {
  Shape.call(this); // call super constructor.
}

// subclass extends superclass
Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;

var rect = new Rectangle();

console.log("Is rect an instance of Rectangle? " + (rect instanceof Rectangle)); // true
console.log("Is rect an instance of Shape? " + (rect instanceof Shape)); // true

rect.move(1, 1); // Outputs, 'Shape moved.' 

Now it explained very nicely how inheritance can be done. But I wanted to know what exactly is the need of this line of code

Rectangle.prototype.constructor = Rectangle;

Does it really required. Eliminating that does not create any issue while running. Am i missing something important here or Does it means optional?