haXe seems to come within inches of your idea: Inferred static compilation for multiple VM/source targets with a "trapdoor" into the target's dynamic typesyste

haXe seems to come within inches of your idea: Inferred static compilation for multiple VM/source targets with a "trapdoor" into the target's dynamic typesystem. JS-like syntax. Macro system(still in development but usable). Compiles to reasonably performant C++, although matching hand-written C++ performance is not a goal. I have been using it for several years now with the Flash/JS targets.