Test that pages and workers can send MessagePorts to one another. Should print "DONE" when done.

PASS: evt.ports = [] as expected
PASS: Received message port
PASS: Received response from Worker via MessagePort
PASS: Got port from worker
PASS: Calling MessagePort.postMessage() without parameter threw exception: TypeError: Not enough arguments
PASS: Received final response from worker
PASS: Got 1000 messages
DONE