fast/forms/submit-change-fragment.html is flaky on all platforms.

BUG=384950
TBR=

Review URL: https://codereview.chromium.org/338743002

git-svn-id: svn://svn.chromium.org/blink/trunk@176180 bbb929c8-8fbe-4397-9dbb-9b2b20218538