Before the whole project was killed, Node-ChakraCore had a time travel debugger that worked pretty well. I don't know how easy it would be to port the methods i

Before the whole project was killed, Node-ChakraCore had a time travel debugger that worked pretty well. I don't know how easy it would be to port the methods it used to a chrome extension (my guess is somewhere between difficult and impossible), but browser vendors could implement this natively.