Revert 244240 "IndexedDBFactory now ForceCloses databases."

> IndexedDBFactory now ForceCloses databases.
> 
> Also, IndexedDBContextImpl used to maintain a map of open
> connections. This change also deletes this map, and instead
> relies on one which already exists in IndexedDBFactory.
> 
> BUG=259564
> 
> Review URL: https://codereview.chromium.org/93873017

TBR=cmumford@chromium.org

Review URL: https://codereview.chromium.org/134503003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244273 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244273