Yes, but the benchmark is not "how fast does V8 translate scheme to JS", it's "how fast does V8 run benchmarks in javascript that where translated from scheme some time ago".
Atleast that's how i understand it.
That's true, but machine-generated code can be pretty nutty, depending on what exactly the Scheme2JS compiler does. It's legitimate JS code, but it might not be representative of what JS-written-in-JS looks like.