Set an application badge without platform object

[annevk]

For https://github.com/w3c/push-api/issues/360 I need a way to set an application badge when there's no platform object involved. All the relevant permission checks should still apply. The only permission the origin making the request (which should be an argument) can be understood to have is the notification permission.

[marcoscaceres]

Right, it should take a URL instead a platform object. The URL identifies the application... or a top-level traversable (tab or tabs), which the badge would be set to.