Global rename of the class "IDBBackingStore" to "IDBBackingStoreLevelDB"

Global rename of the class "IDBBackingStore" to "IDBBackingStoreLevelDB"

Rubberstamped by Anders Carlsson (And Andreas Kling wanted to, but he wasn’t around)

* Modules/indexeddb/IDBTransactionBackendInterface.h:
* Modules/indexeddb/leveldb/IDBBackingStoreLevelDB.cpp:
* Modules/indexeddb/leveldb/IDBBackingStoreLevelDB.h:
* Modules/indexeddb/leveldb/IDBCursorBackendLevelDB.cpp:
* Modules/indexeddb/leveldb/IDBCursorBackendLevelDB.h:
* Modules/indexeddb/leveldb/IDBDatabaseBackendLevelDB.cpp:
* Modules/indexeddb/leveldb/IDBDatabaseBackendLevelDB.h:
* Modules/indexeddb/leveldb/IDBFactoryBackendLevelDB.cpp:
* Modules/indexeddb/leveldb/IDBFactoryBackendLevelDB.h:
* Modules/indexeddb/leveldb/IDBObjectStoreBackendLevelDB.cpp:
* Modules/indexeddb/leveldb/IDBObjectStoreBackendLevelDB.h:
* Modules/indexeddb/leveldb/IDBTransactionBackendLevelDB.cpp:
* Modules/indexeddb/leveldb/IDBTransactionBackendLevelDB.h:
* Modules/indexeddb/leveldb/IDBTransactionBackendLevelDBOperations.cpp:
* Modules/indexeddb/leveldb/IDBTransactionBackendLevelDBOperations.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@157671 268f45cc-cd09-0410-ab3c-d52691b4dbfc