The spec references database version being the empty string. It's probably a leftover from older versions of the spec. But now the version is a unsigned  long, so it shouldn't be set to a string.


http://dvcs.w3.org/hg/IndexedDB/raw-file/tip/Overview.html#object-store-concept

Change:
  When a new database is created it doesn't contain any object stores
  and has the empty string as version.
To:
  When a new database is created it doesn't contain any object stores.


http://dvcs.w3.org/hg/IndexedDB/raw-file/tip/Overview.html#widl-IDBDatabaseSync-version

Change:
  This attribute has the empty string value when the connected database
  is first created.
To:
  This attribute is 0 when the connected database is first created.