Personally, I'd like to see a Scheme or ML dialect, but I'm not one to exclude good languages: I'd love to see some way to portably, reliably, and safely extend

Personally, I'd like to see a Scheme or ML dialect, but I'm not one to exclude good languages: I'd love to see some way to portably, reliably, and safely extend all browsers to support new language VMs - including languages like Dart, Python, Ruby, Lisp, etc. - without resorting to huge blobs of JavaScript that half-heartedly implement a half-useful language. Things like ASM.js are interesting, but not really helpful, in my mind, as it just adds another unnecessary layer of overhead just to be able to implement something interesting in a language suited to it. I just wish browser vendors saw this the way I do.