LeakExpectations: Unsuppress false positives from ServiceWorker tests

TBR=hajimehoshi
NOTRY=true
BUG=364390

Review URL: https://codereview.chromium.org/427483002

git-svn-id: svn://svn.chromium.org/blink/trunk@179004 bbb929c8-8fbe-4397-9dbb-9b2b20218538