readAsText (blob, encoding = undefined) {
    webidl.brandCheck(this, FileReader)

    webidl.argumentLengthCheck(arguments, 1, { header: 'FileReader.readAsText' })

    blob = webidl.converters.Blob(blob, { strict: false })

    if (encoding !== undefined) {
      encoding = webidl.converters.DOMString(encoding)
    }

    // The readAsText(blob, encoding) method, when invoked,
    // must initiate a read operation for blob with Text and encoding.
    readOperation(this, blob, 'Text', encoding)
  }
@see https://w3c.github.io/FileAPI/#dfn-abort