<!DOCTYPE html>
<html>
<head>
    <script id="worker1" type="javascript/worker">
      self.onmessage = async function (e) {
        const canvas = new OffscreenCanvas(82, 127)
        canvas.getContext('2d', {})
        canvas.width = 134
        await canvas.convertToBlob({})
        canvas.transferToImageBitmap()
      }
    </script>
    <script>
      window.addEventListener('load', () => {
        const blob = new Blob([document.querySelector('#worker1').textContent], { type: 'text/javascript' })
        const worker = new Worker(window.URL.createObjectURL(blob))
        worker.postMessage([], [])
        setTimeout('self.close()', 500)
      })
    </script>
</head>
</html>