Test behavior of Document.replaceChild() when oldChild is null.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".

PASS document.replaceChild(document.firstChild, null) threw exception TypeError: Failed to execute 'replaceChild' on 'Node': parameter 2 is not of type 'Node'..
PASS successfullyParsed is true

TEST COMPLETE