Then the bastard tries to willingly access x to equate it to undefined, but that can't work since x is undefined and yields a ReferenceError (rendering the third expression moot).
The monks answers of document.all is not applicable since document.all is a live set of data which can be nothing or everything.
Who even introduced document.all? I bet it was microsoft...
I stumbled upon two or so, but they were abandoned early on.