Web Push: Empty messages don't need crypto headers

[ghost]

IIRC, it's okay to omit the Content-Encoding and Encryption headers for push messages without a body. The DOM API can distinguish these from empty encrypted messages: pushEvent.data === null for the former; pushEvent.data.text() === "" for the latter.

[ghost]

Though, now that I look at the latest spec, I see pushEvent.data is required.

[ghost]

From IRC:

15:40 — mt kitcambridge, benbangert: re: encryption, the idea is that a push without any data would be fine, but we would return no data object. An empty message is different, it should include an authentication tag then.

Sounds like the distinction is still relevant, and the spec should be updated accordingly.