negative offset after remux with libvpx 1.8.1

[d3im]

I'm getting negative offset after remux that makes mse error in Chrome - it can't add chunk to buffer with negative offset.

[d3im]

I exported webm at 50 fps instead of original 59.94 and remux didn't made error of negative offsets, but it's not fix for original problem.

[acolwell]

I know this was filed a long time ago, but if you are still having to work around this issue and can send me an example file, I'd be happy to work on a fix.