Remove passing tests from OilpanLeakExpectations.

BUG=389042
TBR=kouhei@chromium.org

Review URL: https://codereview.chromium.org/356993003

git-svn-id: svn://svn.chromium.org/blink/trunk@177067 bbb929c8-8fbe-4397-9dbb-9b2b20218538