In order to be able to unittest javascript source that doesn't intensely use the DOM it would be really useful to be able to run it on a javascript interpreter like spidermonkey. JavaScriptCore has jsc but in order to get it you have to build it yourself from trunk. It would be really useful to have it released with WebKit nighties.
Fixed in r34725. This will be in a nightly in the next nightly that is built. The jsc binary lives at JavaScriptCore.framework/Resources/jsc.