Ensure callback objects held by the Indexed DB
dispatcher are released before WebKit and V8
are torn down, since the callback objects hold
V8 handles.

BUG=308988
TBR=dgrogan@chromium.org

Review URL: https://codereview.chromium.org/50333004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232620 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232620