Servo relies on firefox's JS runtime spidermonkey, written in C++.
Moreover, a significant fraction of JS vulnerabilities are logic errors in the JIT, so even if the JIT itself is memory safe, that doesn't make the resulting code free of vulnerabilities.
Windows ME was the worst Windows though.
Hard agree.
Windows 98SE SP2 was the best
Vista was the worst in my book. And Vista was actually the real turning point when C# started to infect Windows.