title: prototype chain fails to retrieve a property set in Function.prototype
body: <p>When I add a property to <code>Function.prototype</code>, why does it disappear from the chain?
  Why is the property <code>yyy</code> (which is in the property chain) undefined?</p>
  <pre class="lang-js prettyprint-override"><code>function Shape() { }
  Shape.prototype.xxx = 111;
  Function.prototype.yyy = 222;
  
  let x = new Shape;
  
  console.log(x.xxx) // 111
  console.log(x.yyy) // undefined???
  </code></pre>