Blink gardening: mark storage/websql/sql-error-codes.html as flaky on linux

It fails on Linux Leak bot a lot

BUG=417752
TEST=bots
TBR=dumi@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/602043004

git-svn-id: svn://svn.chromium.org/blink/trunk@182695 bbb929c8-8fbe-4397-9dbb-9b2b20218538