title: HTMLAnchor element download not working in Typescript
body: <p>I can't get the HTMLAnchor element's download property to work under TypeScript.
  I'm using the following code:</p>
  
  <pre><code>var element = document.createElement('a');
      element.href = 'data:attachment/csv,' + encodeURIComponent(csvContent);
      element.target = '_blank';
      element.mimeType = "attachment/csv";
      element.download = 'Report.csv';  /* #debug 030314  this line fails */
      document.body.appendChild(element);
      element.click();
  </code></pre>
  
  <p>It seems that the download property isn't supported in TypeScript. Is there a work-around, that adds the .csv suffix to the file?
  - Is it possible to bypass TypeScript and call the Javascript code directly?</p>