HTMLElement.blur() should cancel all the focus in sub tree?

[mantou132]

Example:

document.body.innerHTML = `
  <my-ele>
    <div tabindex=1>focusable</div>
  </my-ele>
`
document.querySelector('div').focus();
document.querySelector('my-ele').blur();
document.body.append(`current active element: ${document.activeElement.tagName}`);

Firefox: current active element: DIV
Chrome: current active element: BODY
Safari: current active element: BODY

[domenic]

blur() runs the unfocusing steps on the element. That algorithm can be a bit confusing, but to me it looks like the spec matches Firefox's behavior right now: old chain consists of the div and the document, so step 4 returns without doing anything.

I tried looking at Chromium code but it's pretty confusing and not very similar to the spec, so it's not clear what the right fix would be here.