From Rosetta Code

The name escapes me, but I believe Mozilla's JS engine has its own name, which is separately available as well. If I could remember the name, I'd suggest creating a page for that, making that the JS implemenation, and indicating that Firefox uses it. --Michael Mol 14:44, 23 April 2010 (UTC)

SpiderMonkey, called TraceMoney in FF 3.5 apparently. --Mwn3d 14:52, 23 April 2010 (UTC)