Way to clone for other document contexts

[stuartpb]

If this were refactored to not implicitly reference the global document, this could be reused to create elements in other document contexts, eg. within iframes (contentDocument) or Shadow DOMs.

[stuartpb]

Would this.document be enough? And then new cre(); cre.document = whateverForeignContext would take care of that. (And the normal inheritance to window would resolve it in the normal case, or something like that - this might also need some consideration in the context of Web Workers.)