Shouldn't be too hard to make a library that would allow this. Would you be interested in that ? So let's say something like the following example, would you use it?

This should be possible:

    <script src="some.url/gopherjs.js">
    <script type="application/golang">
      package main

      import "fmt"

      func main() {
        fmt.Printf("yeah baby\n") // Effectively console.log
      }
    </script>

Obviously this would take more than a bit of time to start up (seconds), but the idea is of course that you don't do this once you deploy to production, and replace by inline webassembly.