ServiceWorker: Re-enable http/tests/serviceworker/skip-waiting.html test.
ServiceWorker: Re-enable http/tests/serviceworker/skip-waiting.html test.

The flaky timeout issue was fixed by: https://codereview.chromium.org/821853002/

BUG=443046

Review URL: https://codereview.chromium.org/825193002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@187703 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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