Re: [service-workers-tests] Fix crash with script constructed ExtendableEvent().waitUntil(). (#4671)

Notifying @ehsan and @mkruisselbrink. *([Learn how reviewing works](https://github.com/w3c/web-platform-tests/blob/master/README.md#test-review).)*

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View on GitHub: https://github.com/w3c/web-platform-tests/pull/4671#issuecomment-276469761

Received on Tuesday, 31 January 2017 19:42:59 UTC