deleteDatabase error case should never happen #74

The steps for deleteDatabase start off with

1. Let request be a new open request.
2. Queue a task to run these substeps:
   1. Let result be the result of running the steps for deleting a database, with the origin of the IDBEnvironment used to access this IDBFactory, name, and request.
   2. If result is an error set the error of request to result and dispatch an event at request. The event must use the Event interface and set the type attribute to "error". The event does bubble but is not cancelable.

But the "steps for deleting a database" never return an error. This may be legacy from timeout and/or sync behavior?