The toolchain, yes. I'm not sure about the libraries - especially the ones that provide the glue to the JS world (or DOM, directly). I heard there is something, say, SDL support for asm.js or emscripten, but I don't think there's a large and stable ecosystem. More like "some stuff patched to some extent".

Oh, and I think in webdev, there is a lot of... err... modern creative and innovative guys and gals out there who are always happy to rewrite the world again, because the last week's tech isn't cool anymore.