[js] getComputedStyle argument type

[mockey]

I guess js.html.Window.getCompiutedStyle should better use DOMElement (a.k.a. Element) instead of Element (a.k.a .HTMLElement) for its argument type, shouldn't it?

[RealyUniqueName]

Yeah. According to MDN getComputedStyle accepts an argument of JS's Element, which is called DOMElement in our externs for some reason.
And our Element is actually HTMLElement in JS.
I guess there may be other errors in our externs caused by this mess.

[haxiomic]

Follows on from the discussion on DOMElement / HTMLElement -> Element differences and remapping
#4081

I think the original remap of Element -> HTMLElement was done because many methods technically return Elements but practically return HTMLElements

It would be great to see if we can straighten this out for 4.1. My current thinking on how to improve the externs going forward is to use the TypeScript extern generator as a base for a rewrite, since TS put a lot of effort into getting the html externs perfect

[mockey]

I think the original remap of Element -> HTMLElement was done because many methods technically return Elements but practically return HTMLElements

An HTMLElement is always an Element as well (technically and practically). Why exclude SVGElements that way?

I always thought that this weird remap was mainly done because of the js.html namespace. The original names all have the HTML prefix like HTMLDivElement which sort of translates to html.DivElement. Of course this is not the case for a lot of other classes under js.html (because they are not HTML* elements). And there are classes like js.html.HTMLDocumentand there is js.html.svg.* for SVGElements and there are subfolders like js.html.midi where the classes keep their prefix, e.g. MIDIAccess and js.html.idb where they don't, e.g. IDBCursor...
All in all it's a mess, but the worst is that Element -> js.html.DOMElement and HTMLElement -> js.html.Element remap.

My suggestion would be:

• use another namespace like js.dom or js.web (according to MDN it's a "Web API")
• stick to the original "Web API" names (as weird as they might be, like HTMLHtmlElement)

[haxiomic]

If it would go down well with the community I'd love to do as you suggest @mockey and rebuild the externs without any renaming. I like your suggestion of moving to js.dom or js.web and deprecating js.html. Definitely something on my mind for the next pass at externs.

Big change of course because so many projects rely on these but I guess we can always add --remap js.html js.web to extraParams in a compat repo

To ball-park, the timeline for something like this is out at around 6 months because I'd want to do it as part of the html-externs rewrite