Offline cache prompt shown; Allow button does not dismiss.

Testing the TBB 3.5 rc1 build 3 on MacOS 10.9, we saw that an offline data prompt is displayed but clicking "Allow" does not dismiss the prompt.

Steps to reproduce:

1. Open http://stevesouders.com/tests/clearbrowser/save.php
2. Click "Allow" in the "This website is asking to store data for offline use" prompt.
3. Notice that the prompt is not dismissed.

The following message is shown on the Error Console: NS_ERROR_NOT_AVAILABLE: Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIOfflineCacheUpdateService.scheduleUpdate] @ chrome://browser/content/browser.js:14006