Rename the first argument of defineElement from type to localName

[rniwa]

defineElement's first argument should be renamed to localName.

type is a very generic term and could refer to anything whereas localName in the context of DOM API is understood to refer to a specific meaning and also matches the definition of createElement.

[domenic]

Although I agree type is not a great word, I think it's important to distinguish from localName, because of the type extensions/ { is } version.

Assuming #408, then if you do

document.defineElement("super-a", XFoo, { extends: "a" });

document.createElement("a", { is: "super-a" });

then the resulting local name of such elements will be "a", not "super-a".

I also think it's important to have a term for what is currently "valid custom element type".

[annevk]

Maybe just use "name"? (It does somewhat make sense not to use localName here since it'll have different restrictions placed on it for now per the ASCII issue.) And make "custom element type" not refer to the name, but to a particular brand of element.

[rniwa]

Oh I see. Yeah, name would be better.