Proposal: Element.computedLang

[nuxodin]

Hi,

If you want to output element-related text with JavaScript, you like to use the language that corresponds to the element. For example, in custom elements.

The current approach is to search for .closest([lang]).
But if it is not present, or incorrect, it becomes more difficult.

It would be desirable to have a property Element.computedLang that uses the same procedure as internally the CSS pseudo-class :lang().

What do you think?

[domenic]

Dupe of #7039.