命令行 cscript 不能遍历出 对象中已设置的 toString 键

Question

function $trace($var){
	if('console' in this)
		console.log($var); // Browser
	else if('WScript' in this)
		WScript.Echo($var); // Windows
};

$trace('----- ----- 1 ----- -----');
var o = {};
var b = new Boolean(o.hasOwnProperty('toString'));
$trace('toString in o : '+b.toString());
$trace('----- ----- 2 ----- -----');
o['toString'] = function(){return '1234'};
$trace('set o["toString"]');
$trace('----- ----- 3 ----- -----');
b = new Boolean(o.hasOwnProperty('toString'));
$trace('toString in o : ' + b.toString());
$trace('----- ----- 4 ----- -----');
var bFound = false;
for(var key in o)
{
	if(key === 'toString')
		bFound = true;
	$trace('for ... in loop : ' + key);
}
if(bFound == false)
	$trace('why no "toString" ?');
$trace('----- ----- 5 ----- -----');
$trace('o toString : ' + o);

浏览器中执行（例如 IE 10）

----- ----- 1 ----- -----
toString in o : false
----- ----- 2 ----- -----
set o["toString"]
----- ----- 3 ----- -----
toString in o : true
----- ----- 4 ----- -----
for ... in loop : toString
----- ----- 5 ----- -----
o toString : 1234

Window 下命令行 cscript 执行

----- ----- 1 ----- -----
toString in o : false
----- ----- 2 ----- -----
set o["toString"]
----- ----- 3 ----- -----
toString in o : true
----- ----- 4 ----- -----
why no "toString" ?
----- ----- 5 ----- -----
o toString : 1234

这个是什么问题？cscript 缺陷么？

Answer 1

=.= 求解