| Tests support for 'once' member in AddEventListenerOptions. | |
| On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". | |
| document.body.addEventListener('test', listenerFunction, { 'once': true }) | |
| PASS listenerCallCount is 0 | |
| document.body.dispatchEvent(new Event('test')) | |
| PASS listenerCallCount is 1 | |
| document.body.dispatchEvent(new Event('test')) | |
| PASS listenerCallCount is 1 | |
| PASS successfullyParsed is true | |
| TEST COMPLETE | |