As you can see in this article . WebAssembly will be the new standard and will finally provide us near-native performance for web.
Even Unity will support it. It would be a shame that the new Scirra product that is focused in web, to not do it.
Actually, i think that does not make sense to Scirra writes a new runtime and let WebAssembly aside.
WebAssembly is the future of web games/apps.