IndexedDB in Web Worker in Firefox

I am trying to use indexedDB in Firefox 12 in a web worker .

dbRequest = mozIndexedDB.open("mydb","test db");

However, Firefox shows an error: mozIndexedDB undefined

I tried a few others, such as self.mozIndexedDB, moz_indexedDBSyncbut to no avail.
It works fine in Chrome with webkitIndexedDB.

Any help would be greatly appreciated ...