Tests $x for iterator and non-iterator types.

$x('42')
42
$x('name(/html)')
'html'
$x('not(42)')
false
$x('/html/body/p').length
1
$x('//a/@href')[0]
href="http://chromium.org"
$x('./a/@href', document.body)[0]
href="http://chromium.org"
$x('./a@href', document.body)
VM:1 Uncaught SyntaxError: Failed to execute '$x' on 'CommandLineAPI': The string './a@href' is not a valid XPath expression.
    at <anonymous>:1:1
(anonymous) @ VM:1
console-xpath.js:26 complete