Indexed DB: Remove vendor prefix removal from tests

LayoutTests/storage/indexeddb/metadata-race-expected.txt

 Ensure IndexedDB transactions created before open onsuccess have correct metadata
 
 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 = "metadata-race.html"
 indexedDB.deleteDatabase(dbname)
 indexedDB.open(dbname)
 
 prepareDatabase():
 db = event.target.result
 store = db.createObjectStore('store')
 store.createIndex('index', 'keyPath')
 transaction = event.target.transaction
 PASS index = transaction.objectStore('store').index('index') did not throw exception.
 
 onTransactionComplete():
 In multiprocess mode, 'complete' event may be dispatched before
 the 'success' arrives with updated metadata. Ensure the new metadata
 is still used for transactions.
 store = db.transaction('store').objectStore('store')
 PASS index = store.index('index') did not throw exception.
 
 onOpenSuccess():
 db = event.target.result
 store = db.transaction('store').objectStore('store')
 PASS index = store.index('index') did not throw exception.
 PASS successfullyParsed is true
 
 TEST COMPLETE