Gardening: fast/dom/Window/open-window-min-size.html flaky on Win7 dbg

BUG=231880
TBR=jsbell

Review URL: https://codereview.chromium.org/38303005

git-svn-id: svn://svn.chromium.org/blink/trunk@160412 bbb929c8-8fbe-4397-9dbb-9b2b20218538