[IndexedDB] Fixing early destruction of connection during forceclose

Patch is as small as possible for merging.

Bug: 842990
Change-Id: I9968ffee1bf3279e61e1ec13e4d541f713caf12f
Reviewed-on: https://chromium-review.googlesource.com/1062935
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#559383}(cherry picked from commit 28044cb7ef4488e7278c2b80f0e3a2c3707d03b6)
Reviewed-on: https://chromium-review.googlesource.com/1067057
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/branch-heads/3396@{#662}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
3 files changed