Mark http/tests/serviceworker/fetch-event.html NeedsManualRebaseline

Please manually rebaseline the test.
Rebaseline-o-matic doesn't support rebaselining harness tests with
passing results.

BUG=388375
TBR=nhiroki@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/651473002

git-svn-id: svn://svn.chromium.org/blink/trunk@183559 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Showing only chromium status on chromium page, and both on blink

BUG=405591
NOTRY=true

Review URL: https://codereview.chromium.org/603293002

git-svn-id: svn://svn.chromium.org/blink/trunk@183560 bbb929c8-8fbe-4397-9dbb-9b2b20218538