Resolve add and addAll with undefined instead of responses

[tobie]

Given that add and addAll now only resolve when the full body has been streamed to the cache, resolving with the streamed response risks pushing developers to use an anti-pattern whereby the response is first streamed to the cache before being streamed to the client instead of doing both in parallel.

Proposed resolution: have both add and addAll resolve with undefined.

[tobie]

Think the same holds true of put and delete, actually. Is there any reasons for either put or delete to resolve with a response?

[jakearchibald]

Agreed, and I believe this is how the polyfill (and ts) behaves.

delete should return true/false depending on if anything was deleted.

[KenjiBaheux]

Filed crbug.com/425469 for tracking in Blink

[inexorabletash]

The algorithms in the spec were updated, but the Web IDL was not

[inexorabletash]

Per @annevk the IDL for this would be Promise<void>

[jungkees]

Addressed: ba17a4e. Thanks.