This was discussed some time before, and I guess every using the mobile web application thinks this is a killer addition to the mobile web experience. However, this still isn't implemented.
The reason given in the old post is:
The gotcha is that a lot of android phones really don't have the click accuracy you need to distinguish between up vote, down vote, and show vote split clicks.
Come on people. It is 2015 now. Mobile phones have gone better a lot. Also, there are other solutions at hand that could be implemented.
Can we have a second thought on this feature?