This sounds like the first step in a vision I've had for how the web should evolve. We now have an LLVM frontend for Javascript, so Javascript code can be turned into LLVM bytecode.

The next step would be to swap out the existing Javascript runtimes with this frontend plus a sandboxed backend for the native platform so they can compile Javascript to LLVM bytecode, then to native code.

Finally, you add an extension to the <script> tag to allow loading arbitrary LLVM bytecode, something like <script src="http://some/url/code.llvm" type="text/llvm">.

Once that's in place then you'd be able to execute any language that has an LLVM front end inside the browser environment. Javascript is no longer the sole language of the web, and things like Emscripten and asm.js become obsolete.