[wake-lock] Subtleties of using Document are not specced (#141)

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

== Subtleties of using Document are not specced ==
Wake locks are still tied on the spec level to a document, not a window.

This has the following consequences:

- Need to spec what happens for inactive documents, including when an active document goes inactive. Currently this is not specified.
- Need to spec what happens for documents without a browsing context, e.g. `xhr.responseDoc` or `new Document()`. Currently this is not specified.

Please view or discuss this issue at https://github.com/w3c/wake-lock/issues/141 using your GitHub account