MediaRecorder requestData() always returns empty Blob

I'm working on this bug https://bugs.webkit.org/show_bug.cgi?id=202233 and I wanted to use requestData() but found that in Safari or the MiniBrowser, requestData() always return an empty Blob.

I have try it in Chrome and Firefox and it worked as expected.

To replicate...

 1. Open Safari
 2. Open the Develop Menu
 3. Hover over the Experimental Features list item
 4. Click on MediaRecorder to Enable it
 5. Navigate to https://codepen.io/majov5/pen/LYpaEga
 6. Click on the blue Start Test button at the bottom
 7. Allow access to Microphone & Camera
 8. Click on the Record button at the bottom


Now every 5 seconds the Codepen console will print

[object Blob] {
   size: 0,
   slice: function slice() {...},
   type: ""
}

[Radar WebKit Bug Importer]

<rdar://problem/63601261>

[youenn fablet]

*** This bug has been marked as a duplicate of bug 206929 ***