LeakExpectations: add web-animations-api/player-finish-sample-only.html

NOTRY=true
BUG=379032

Review URL: https://codereview.chromium.org/301243004

git-svn-id: svn://svn.chromium.org/blink/trunk@175095 bbb929c8-8fbe-4397-9dbb-9b2b20218538