[vm][newbie] "hidden classes"

[Casey Ransberger]

I'm curious about a term I heard awhile back while digging through the v8 docs, "hidden classes." The gist was that the VM would effectively implement an (anonymous, it seems) class to shorten method lookup. I have trouble visualizing how that actually helps, and it's been bugging me. 

I may have completely misunderstood, though. I don't have a whole lot of real experience with prototypes. 

Sorry about all the exposition. Here's my actual query: is this an idea that came from the Self VM, and if so, what papers/code should I read to grok it?