Service Worker: re-enable tests impacted by "redundant" on unregister change

Final side of 3-sided patch:
1) Blink r177932 https://codereview.chromium.org/381383005/
2) Chrome r282636 https://codereview.chromium.org/377153003
3) Blink <-- THIS PATCH

BUG=388095

Review URL: https://codereview.chromium.org/389283003

git-svn-id: svn://svn.chromium.org/blink/trunk@178168 bbb929c8-8fbe-4397-9dbb-9b2b20218538