userVisible -> userVisibleOnly
userVisible -> userVisibleOnly

As described at https://github.com/w3c/push-api/issues/137
google/ioweb2016,GoogleChrome/ioweb2016,google/ioweb2016,google/ioweb2016,GoogleChrome/ioweb2016,GoogleChrome/ioweb2016,GoogleChrome/ioweb2016,google/ioweb2016