[ServiceWorker] Fix spelling error: arguement -> argument (#748)

Argument seems to have been misspelled a couple of times in the spec, this fixes those.
You can view, comment on, or merge this pull request online at:

  https://github.com/slightlyoff/ServiceWorker/pull/748

-- Commit Summary --

  * Fix spelling error: arguement -> argument

-- File Changes --

    M spec/service_worker/index.html (12)

-- Patch Links --

https://github.com/slightlyoff/ServiceWorker/pull/748.patch
https://github.com/slightlyoff/ServiceWorker/pull/748.diff

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/pull/748