Don't share ServiceWorkerHandle between provider hosts.

Don't share ServiceWorkerHandle between provider hosts.

This prevents an ASSERT failure in ServiceWorker::from() when it's
passed an existing SW from a different execution context. Since
ServiceWorkers minted in different documents should have
different prototypes, we shouldn't expect JavaScript equality so don't
need to share ServiceWorkerHandles.

BUG=400980
TEST=https://codereview.chromium.org/443883003/

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287852

[falken, 2014-08-06 09:29:38]

PTAL

Follow-up to https://codereview.chromium.org/412833002

Although register() is changing to resolve to a registration, we still should
get this correct (and not crash). We'll have to use similar code for de-duping
installing/waiting/active/controller as in crbug.com/400602

[nhiroki, 2014-08-06 09:40:09]

LGTM. Thank you for working on this!

[falken, 2014-08-06 15:20:18]

The CQ bit was checked by falken@chromium.org

[commit-bot: I haz the power, 2014-08-06 15:21:23]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/falken@chromium.org/440403002/1

[commit-bot: I haz the power, 2014-08-06 20:54:04]

Change committed as 287852