Html 5 Local Storage not persistent in firefox

I made a simple function

localStorage.setItem('foo', 'bar')  
alert(localStorage.getItem('foo'));

If I run it like this it works. If I remove the first line after I run it once and I let only this

alert开发者_运维百科(localStorage.getItem('foo'));

I get a null value in Firefox 3.6.12 In chrome it works.

Any ideas ?

It's a bug [ https://bugzilla.mozilla.org/show_bug.cgi?id=507361 ]