I think HTMLElement.call should throw if there’s not an associated tag name.
However exactly how that association happens, I am not sure.
JavaScript can’t rely on the 'constructor' property. Shadowing the
tagName attribute on the prototype is not ideal, because it may be
mutable and it would be co
>From the discussion about "x-" prefixed names another question crossed my
mind: Suppose an author defines a component, but doesn't register a tag
name. AFAICT, at this point nothing prevents him from inserting such a new
element into the DOM. E.g.:
function MyNewElement() {
HTMLEle
