Broken prototype chain for elements

🐛 bug report

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project
  adheres to.
• I have searched the issue tracker for an issue that matches the one I want
  to file, without success.

Description of the problem

The class hierarchy for elements is broken.

EventTarget -> Node -> Element -> HTMLElement -> HTMLButtonElement

How has this issue affected you? What are you trying to accomplish?

Using an element as a parameter to e.g. Range.setStart results in TypeError: Failed to execute 'setStart' on 'Range': parameter 1 is not of type 'Node'.

Codesandbox is our primary platform for online reproduction at @testing-library/user-event.
user-event@14 supports Selection. With this bug all pointer interactions with elements that don't implement their own selection (everything except <input>,<textarea>) result in an error.

To Reproduce

test('Element extends Node', () => {
    expect(document.body).toBeInstanceOf(Node) // fails
})

test('select per Range', () => {
    document.body.innerHTML = `<div>foo</div>`

    const range = new Range()
    range.setStart(document.body.firstChild, 0) // throws
    range.setEnd(document.body.firstChild, 1)

    document.getSelection().addRange(range)
})

Link to sandbox: link (optional)

Your Environment

Start with the provided reproduction tests and the linked CodeSandbox, focusing on document.body, Node, Range.setStart, and Range.setEnd. Confirm the broken prototype relationship and Range failures, then verify that elements follow EventTarget → Node → Element and that both range operations accept the reproduced element or text-node inputs.