[GopherJS] insertAfter - Insert New Node After Reference Node

insertAfter - Insert new node after reference node via GopherJS. (opposite of insertBefore).

referenceNode.Get("parentNode").Call("insertBefore", newNode, referenceNode.Get("nextSibling"))

This comes from answer of [2].

Tested on: Ubuntu Linux 15.10, Go 1.6.

References:

[1]	GopherJS - A compiler from Go to JavaScript (GitHub, GopherJS Playground, )