This tests accessing the length after accessing (length + 1)-th item in HTMLCollection doesn't cache a wrong length.
On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
PASS children = container.children; children.length is 0
PASS container.appendChild(span); children[1]; children.length is 1
PASS container.removeChild(span); children.length is 0
PASS successfullyParsed is true
TEST COMPLETE