Indexed DB: Remove vendor prefix removal from tests

LayoutTests/storage/indexeddb/transaction-rollback-expected.txt

 Test IndexedDB transaction rollback.
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
-indexedDB = self.indexedDB || self.webkitIndexedDB || self.mozIndexedDB || self.msIndexedDB || self.OIndexedDB;
-
 dbname = "transaction-rollback.html"
 indexedDB.deleteDatabase(dbname)
 indexedDB.open(dbname)
 db.createObjectStore('myObjectStore')
 PASS db.objectStoreNames.length is 1
 setVersionComplete():
 transaction = db.transaction(['myObjectStore'], 'readwrite')
 store = transaction.objectStore('myObjectStore')
 store.add('rollbackValue', 'rollbackKey123')
 addSuccess():
 PASS event.target.result is "rollbackKey123"
 store.openCursor()
 openCursorSuccess():
 cursor = event.target.result
 abortCallback():
 Transaction was aborted.
 transaction = db.transaction(['myObjectStore'], 'readonly')
 store = transaction.objectStore('myObjectStore')
 store.get('rollbackKey123')
 getSuccess():
 PASS event.target.result is undefined
 PASS cursor.value is "rollbackValue"
 PASS successfullyParsed is true
 
 TEST COMPLETE