That feature's not gone, but I'm unsure as to the circumstances when it pops up. The claim victory button popped up on this game for me:
http://en.lichess.org/RWTmxAHZ/blackThe problem is the ones who force you to wait don't close their windows, either.
I just had one today as well now. But it isn't always the case that they force you wait. I have MANY games where the red disconnect icon comes up that they've left the game and it NEVER gives me an option to claim draw or victory. Today has been a rare exception, and I think it's because they legitimately got disconnected from the server rather than closing their browser window in angst. I'm just saying maybe it should be revamped to be flag when they leave the table for more than 2 minutes or something. There really is no way to stop someone from just walking away from their computer and forcing you to wait, though. You could do that in a legitimate OTB tournament really...
I just had a thought, today being the Saturday before Xmas...
The Internet may be so overwhelmed that disconnects and lichess' ability to detect walk-offs, real or caused by glitches, may be being affected?