Some native js function do not have an "apply" member. But this should not affect the code which checked if the apply is null before use it:

if (document.body.appendChild.apply != null)
{
     // find the other way...
}

However above code doesn't work in ie8, it will cause code error and block subsequent execution.

The temporary (I guess this is a bug, there is no unknown type in ecma) workaround is to check typeof (document.body.appendChild.apply) != "unknown".