Yes, JITs in WebKit and Gecko showed up around the same time as v8, or a little earlier even. And the WebKit JIT (Nitro) beat v8 on various benchmarks.

It's still possible v8 somehow sparked those other JITs, if before it was public the developers of WebKit and Gecko learned of v8 and stepped up their game. But, I don't know if that's true or not.

Anyhow, it's an impressive achievement that people still mention v8 as the reason JavaScript is fast, when it isn't the fastest today, and wasn't the first to be fast historically. Although, it is certainly a worthy VM, just one among several.