They emulated it but they explained it in a blue post.
It just emulates it, but it is not the real thing and if you played on a 1.12 client recently, you realize there is a major difference on how things get batched.
Edit: Btw khlause i found out today its impossible for me to sap rogues with imp. stealth on this client. I run 130-150 MS due to my location and even with heightened senses and spamming tab/sap i end up leaving stealth everytime without doing anything. Rogue does not need to sprint or anything (i usually see him/her first due to nelf racial), just move. If he moves I always leave stealth while doing nothing.
Its really great.