Layout Test fast/history/history_reload.html is flaky

BUG=311301
TBR=falken@chromium.org

Review URL: https://codereview.chromium.org/40303004

git-svn-id: svn://svn.chromium.org/blink/trunk@160475 bbb929c8-8fbe-4397-9dbb-9b2b20218538