Gardening: mark test as crash

fast/filesystem/workers/file-writer-write-overlapped.html has been
crashing on debug builds for a long time.

TBR=tasak@chromium.org
BUG=86340

Review URL: https://codereview.chromium.org/23189007

git-svn-id: svn://svn.chromium.org/blink/trunk@156159 bbb929c8-8fbe-4397-9dbb-9b2b20218538