Node: Fix calls to insertBefore() with one argument

[tindzk]

No description provided.

[sjrd]

Actually, MDN says that both arguments are required. The default value should therefore be removed altogether.

[sjrd]

Note that the value put after = doesn't matter to the compiler in a JS facade. It only serves documentation purposes. So putting null there will not make the compiler add a null if you don't specify the second argument.

[tindzk]

Ok, thanks for clearing this up. I updated the commit accordingly.

[sjrd]

LGTM, thanks.