Everyone optimizes for their own benchmarks. You can say it's dodgy, but that's really just an argument in favor of real-world tests instead of microbenchmarks like this one. You don't have to 'rig' a microbenchmark to come out the winner; you just pick the right microbenchmark, because it's not a real world scenario.

Given the lack of evidence to support actual cheating you should probably just apply occam's razor here and assume it's actually faster. Or you could use the dark, hidden secrets of 'view source' to read the JS yourself. It has comments!