title: Override constructor in Date subclass
body: <p>I would like to create a new <code>Date</code> descendant class and override the constructor:</p>
  
  <pre><code>export class MyDate extends Date {
    constructor(str: string) {
      super(str);
    }
  }
  </code></pre>
  
  <p>Now, if I create a <code>MyDate</code> object, it doesn't work :</p>
  
  <pre><code>var myDate = new MyDate("2016-10-20T12:30:00+0200");
  console.log(myDate.toDateString()); // it crashes, myDate is incorrect
  </code></pre>
  
  <p>I get <code>TypeError: Method Date.prototype.toDateString called on incompatible receiver [object Object]</code>.</p>
  
  <p>How can I override the <code>Date</code> constructor? Is it possible?</p>