Tests that navigator.serviceWorker always returns the same object.

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


PASS navigator.serviceWorker.foo is undefined.
PASS navigator.serviceWorker.foo is 1
PASS navigator.serviceWorker.foo is 1
PASS navigator.serviceWorker.foo is 1
PASS successfullyParsed is true

TEST COMPLETE