consider a method to force immediate disk deletion even if there are live Cache/Response js objects

[wanderview]

See:

https://bugs.chromium.org/p/chromium/issues/detail?id=782869#c5

If a site wants to delete a large Cache immediately, they may not want to wait for a GC a run. We should consider allowing them to disconnect their js wrappers or perhaps add a "force" option to the delete() method.

[inexorabletash]

FWIW, on the Chrome side we've been talking about an internal clear operation that would atomically delete all entries in a cache, and using this in conjunction with delete when the user clears browsing data so that the space is reclaimed without waiting for SW reload/GC, and without introducing a new state.

cc: @bsittler

[wanderview]

For the quota eviction or user deletion cases I believe we currently immediately delete and make any use of the Cache object reject with InvalidStateError. Might need to verify that, though.

[wanderview]

FWIW, I do think we should spec the behavior for "cleared by browser" when there are live objects being used.