IndexedDB: Remove unnecessary uses of "using"

Bug: 717812
Change-Id: Ia4e44651b08bb293b175db0c3d92106ebb3f8043
Reviewed-on: https://chromium-review.googlesource.com/c/1366271
Commit-Queue: Chase Phillips <cmp@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616828}
12 files changed