How to enable HTML client-side SQL database in embedded webkit app (test app on github)

Question

I've got a super simple little OS X app with a minimal embedded webkit view that needs client-side SQL database support enabled. I've put the test app up on github but just can't get the client-side storage working.

I'm using Xcode v3.2.3 with the WebKit framework it provides, but have also tried using the webkit nightly without luck.

I'm setting the preferences via a 'web' outlet:

WebPreferences *prefs = [web preferences];
[prefs _setLocalStorageDatabasePath:@"/tmp"];
[prefs _setLocalStorageDatabasePath:@"/tmp"];
[prefs setDatabasesEnabled:YES];
[prefs setLocalStorageEnabled:YES];
[prefs setDeveloperExtrasEnabled:YES];

If anyone could fork the app on github or point out what else I need to be doing, it'd be very much appreciated :)