Yup, it looks like they pulled that feature unfortunately. I know of no alternate way to accomplish the same thing.

 

I believe they tried to automate it more with the Adaptive Backlight and Sunlight Enhancement. If you want more control, I would suggest Velis Auto Brightness - https://play.google.com/store/apps/details?id=com.velis.auto.brightness or CF.lumen - https://play.google.com/store/apps/details?id=eu.chainfire.lumen Velis has CF.lumen built into it. I have not used it with my One but Velis gets a good amount of praise for its work. Might be worth checking out. The XDA thread is here - http://forum.xda-developers.com/showthread.php?t=1910521 and the developer and others are very helpful. Let us know how it works out for ya.