[ServiceWorker] Break SW interfaces tests into separate tests.

Previously a single test was testing multiple interfaces. A failure in
one interface resulted in other interfaces not being tested. This change
breaks up the test into separate tests per interface.

BUG=none
R=jsbell

Review URL: https://codereview.chromium.org/703763005

git-svn-id: svn://svn.chromium.org/blink/trunk@184929 bbb929c8-8fbe-4397-9dbb-9b2b20218538