Widen flakiness of fast/dom/Window/open-window-min-size.html.

BUG=231880
TBR=dglazkov

Review URL: https://codereview.chromium.org/103633007

git-svn-id: svn://svn.chromium.org/blink/trunk@164279 bbb929c8-8fbe-4397-9dbb-9b2b20218538