TorBrowser 5.0a3 acting very odd with e.g. Twitter due to IndexedDB

I'm experiencing numerous problems with Twitter's web interface with the latest alpha version of TorBrowser. I haven't seen this on other websites so I'll enumerate issues here:

• keyboard shortcuts (e.g., opening a tab with ctrl-t, saving a bookmark with ctrl-d) don't work while in the twitter tab but work elsewhere
• images aren't displayed
• trending topics & follow suggestions aren't displayed
• twitter doesn't automatically load/queue new tweets

All of these sound like JS issues, but even whitelisting twitter.com and twimg.com in NoScript didn't seem to make a difference.