TraceMonkey, meanwhile--which is SpiderMonkey's original just-in-time (JIT) compiler, predating -- is being retired, he added.

"With the improvements that type inference made to JaegerMonkey, TraceMonkey simply isn't needed any more," Nethercote explained. "Furthermore, it's a big hairball that few if any JS team members will be sad to say goodbye to."

Then there's IonMonkey, SpiderMonkey's third JIT compiler, which is expected to generate code that's both faster and smaller in size.

An Ever-Closer Race

Chrome rose from 16.20 percent of the desktop browser market in September to 17.62 percent in October, Net Applications this week, largely at the expense of Microsoft's Internet Explorer, which fell from 54.39 to 52.63 percent. Firefox, meanwhile, increased from 22.48 percent in September to just 22.52 percent in October.