Weird, I'm on almost the exact same version (24.0.1312.57) and it does nothing when typing any number of '['. I have the branded version of Chrome, though, but still, weird!
The problem is fixed now, so the fact that it works shouldn't come as a surprise.
The demo doesn't seem to work on Chrome 25.0.1364.152 m. I'm getting this error whenever I try any of the shortcuts (or when I select a command from the drop down):
Uncaught TypeError: Cannot set property 'curOrigin' of undefined (infer.js:489)
Looks interesting though!
That was another quick update that broke things. I fixed it ~20 minutes after I pushed it, but I guess you exactly hit the window where it was broken.