[wake-lock] What if WakeLockRequest is garbage collected?

mounirlamouri has just created a new issue for https://github.com/w3c/wake-lock:

== What if WakeLockRequest is garbage collected? ==
The spec seems to say that the following will hold a wake lock for ever with no way for the page to fix it:
```javascript
navigator.getWakeLock('screen').then(wakelock => {
  wakeLock.createRequest();
});
```

Please view or discuss this issue at https://github.com/w3c/wake-lock/issues/128 using your GitHub account