LeakExpectations: marquee leak is already fixed

TBR=hajimehoshi
NOTRY=true
BUG=393800

Review URL: https://codereview.chromium.org/431553002

git-svn-id: svn://svn.chromium.org/blink/trunk@179204 bbb929c8-8fbe-4397-9dbb-9b2b20218538