Mark fast/loader/stateobjects/document-destroyed-navigate-back-with-fragment-scroll.html as flaky.

BUG=339265
TBR=jl@opera.com

Review URL: https://codereview.chromium.org/138213008

git-svn-id: svn://svn.chromium.org/blink/trunk@166146 bbb929c8-8fbe-4397-9dbb-9b2b20218538