function isEmpty(node, sourceCode) {
  const start = node.startTag.range[1]
  const end = node.endTag.range[0]
  return sourceCode.text.slice(start, end).trim() === ''
}
Check whether the given element is empty or not.
This ignores whitespaces, doesn't ignore comments.
@param {VElement & { endTag: VEndTag }} node The element node to check.
@param {SourceCode} sourceCode The source code object of the current context.
@returns {boolean} `true` if the element is empty.