[ServiceWorker] Foreign fetch (#751)

Sorry for the delay, here is my foreign fetch pull request for issue #684 again, with some of the changes @jungkees made to it already applied on top.
You can view, comment on, or merge this pull request online at:

  https://github.com/slightlyoff/ServiceWorker/pull/751

-- Commit Summary --

  * Start with trying to spec foreign fetch.
  * Add in some of the foreign fetch fixes jungkees made.

-- File Changes --

    M spec/service_worker/index.html (189)

-- Patch Links --

https://github.com/slightlyoff/ServiceWorker/pull/751.patch
https://github.com/slightlyoff/ServiceWorker/pull/751.diff

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/pull/751