Instead of making new languages to run in the browser, why not make an assembly language for the browser and then we can use what ever language we like and comp

Instead of making new languages to run in the browser, why not make an assembly language for the browser and then we can use what ever language we like and compile to that? It's a pain to develop in one language and then have to use JS. Of course you can use coffee script and such things but if it breaks you're going to have to debug JS code.