[IndexedDB]: Shipping IDBFactory databases()

Removing flag and adding method to virtual/stable/ expected.txt files
for shipping IDBFactory.databases() (IndexedDB database info enumeration
function).

Intent to Ship: https://groups.google.com/a/chromium.org/d/msg/blink-dev/xSf7B0aVxnI/0E05ZEB6DAAJ

Change-Id: Idb3253ed11368f3cc0353756409a0f49c9e61426
Reviewed-on: https://chromium-review.googlesource.com/c/1318536
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Andreas Butler <andreasbutler@google.com>
Cr-Commit-Position: refs/heads/master@{#605571}
6 files changed