Mark inspector/styles/styles-new-API.html as flaky for Win XP

BUG=273119
TBR=tdanderson@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21900004

git-svn-id: svn://svn.chromium.org/blink/trunk@156112 bbb929c8-8fbe-4397-9dbb-9b2b20218538