I always look forward to your shows sigflup, because I know there will be some really unusual technical material in them.  This one is no exception.

I've never heard of emscripten before, but I'm going to have to look into this.  It reminds me of a project a while back to compile C code using gcc to MIPS assembly that would run on a MIPS interpreter in Java.  (Someone billed it as a way to compile C programs that would never buffer overflow.  Not exactly accurate, but the buffer overflows would never corrupt the interpreter's stack.)