Test that no more message events are fired after EventSource.close() is called, even if it means discarding events that were already processed.

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

PASS es = new EventSource("/eventsource/resources/event-stream.php"); did not throw exception.
PASS Got message #1
PASS successfullyParsed is true

TEST COMPLETE