ServiceWorker: Remove unused expectations for LayoutTests

These are accidentally added by r175288.


BUG=n/a
TEST=n/a

Review URL: https://codereview.chromium.org/320423006

git-svn-id: svn://svn.chromium.org/blink/trunk@175878 bbb929c8-8fbe-4397-9dbb-9b2b20218538