Firefox actually throws a
NS_ERROR_NOT_IMPLEMENTED exception when
userVisibleOnly is set to
true, because Firefox relies on its own quota system instead of this option, unlike Google Chrome. One demo app is broken with this change. There’s a plan to remove the support for
PushPermissionDescriptor itself from Firefox so that the option will just be ignored rather than throwing.
PushPermissionDescriptor dictionary has been removed for the compatibility with Google Chrome requiring the
userVisibleOnly option, so that it is now simply ignored in Firefox.