IndexedDB: Disable test pending chromium fix which changes result

Upcoming crrev.com/277583002 will change the behavior of this test
(more compatible with other browsers); disabling for now, and will
re-enable with crrev.com/291243003.

BUG=368271
NOTRY=true
TBR=cmumford@chromium.org

Review URL: https://codereview.chromium.org/296693008

git-svn-id: svn://svn.chromium.org/blink/trunk@174469 bbb929c8-8fbe-4397-9dbb-9b2b20218538