Actually I think it got Self's JIT, at least that the story that the Self people tell. Squeak and Pharo's Morphic UI also came from Self.

http://www.selflanguage.org

I was simplifying. As Self roots are in Strongtalk, wich had as goal making a faster Smalltalk implementation.

Now the closest we have to Self is JavaScript, damaged by DOM and its UI hacks to bend documents into applications.