title: Can't set filename of Blob
body: <p>I'm trying to automatically download a blob like this:</p>
  
  <pre><code>blobGeneratingFunction.then(blob =&gt; {
    // blob =&gt; Blob(3797539) {size: 3797539, type: "image/png"}
    let file = new Blob([blob], { type: 'application/octet-stream' })
    file.name = 'test.png'
    file.download = 'test.png'
    let blobURL = URL.createObjectURL(file)
    window.location.href = blobURL
  })
  </code></pre>
  
  <p>Neither the <code>name</code> or <code>download</code> attribute managed to set the filename, which right now is:</p>
  
  <p><code>f486177d-6f5e-4f96-91a9-8df08e7d9da0</code></p>
  
  <p>How to set the filename propertly?</p>