tables/mozilla/other/slashlogo.html is slow on WinXP

Return slow expectation that was removed at r158050.

BUG=295711
TBR= dpranke@chromium.org

Review URL: https://codereview.chromium.org/24323002

git-svn-id: svn://svn.chromium.org/blink/trunk@158119 bbb929c8-8fbe-4397-9dbb-9b2b20218538