IndexedDB: Provide LevelDB with IDBEnv instead of Env::Default
https://bugs.webkit.org/show_bug.cgi?id=106135

Reviewed by Tony Chang.

IDBEnv only changes the name of the histogram where errors are logged.

* platform/leveldb/LevelDBDatabase.cpp:
(WebCore::LevelDBDatabase::destroy):
(WebCore::LevelDBDatabase::open):
(WebCore::LevelDBDatabase::openInMemory):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139556 268f45cc-cd09-0410-ab3c-d52691b4dbfc