LeakExpectations: suppress failure on serviceworker/installing.html

TBR=hajimehoshi
NOTRY=true
BUG=364390

Review URL: https://codereview.chromium.org/382753003

git-svn-id: svn://svn.chromium.org/blink/trunk@177818 bbb929c8-8fbe-4397-9dbb-9b2b20218538