Suddenly needed: appendChild(form1)

[Evertjan.]

1 var form1 = document.createElement("form");
2 form1.setAttribute("method", "post");
3 form1.setAttribute("action", "http://etc....");
4 form1.setAttribute("target", "myTargetWindow");
5 var hiddenField1 = document.createElement("input");
6 hiddenField1.setAttribute("type", "hidden");
7 hiddenField1.setAttribute("name", "data");
8 hiddenField1.setAttribute("value", myData);
9 form1.appendChild(hiddenField1);
10 //document.body.appendChild(form1); // not needed till sept 2016
11 form1.submit();

Using Chrome browser [54.0.2840.16 beta-m (64-bit) in W10]
why is line 10 suddenly needed to get the submission out,
both in Shortcut manager and Tampermonkey?

Is this a bug or planned behavour?

--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)