The `type` attribute is still there, it only fallbacks to javascript if not set. Nothing besides common sense prevents browsers from shipping with type="text/ruby" support as done here. It's just not a very good idea.
What I'm getting at in a somewhat snarky and roundabout way is that VBScript killed multilanguage support in browsers.
There is hardly any popular language today you could embed and get better performance than JS anyway, except for Lua, which barely qualifies as 'popular'.
Meanwhile there are a hundred cross-compilers/transpilers out there that give you the kind of syntax you want, without requiring a ton of changes in browsers.
PDF: [http://research.microsoft.com/en-us/um/people/emeijer/papers...]