This is not a new feature but a new privilege for you since you have earned 250 reputation. 

[See the Help Centre Page](https://askubuntu.com/help/privileges/view-close-votes)

You can close vote your own questions (on any site), but the vote is no more powerful than usual. This is nice, since it gives the community a chance to help to make a decision about whether the question really deserves to be closed, or might actually be possible to answer in a way that helps others. Questions and their answers are not just here to help the OP after all :)

That said, when I decided to vote to close one of my own questions, I did so, and I was in chat at the time and dropped in a link to it, saying "VTC my question as no repro since the problem got fixed in an update to the application" and a mod kindly saved everyone the trouble...