WebAssembly based parser

Web assembly is already available ( behind flag ) in node 6, so might worth trying it as a next level of "Userspace JIT" approach

Some overview:
https://ia601503.us.archive.org/32/items/vmss16/titzer.pdf

Working wasm examples ( run with node --expose-wasm):

function fib(stdlib, foreign, heap) {
  "use asm";

  var i32 = new stdlib.Int32Array(heap);
  var f64 = new stdlib.Float64Array(heap);
  var imul = stdlib.Math.imul;

  function fib(n) {
    n = n|0;
    if (n >>> 0 < 3) {
      return 1|0;
    }
    return (fib((n-1)|0) + fib((n-2)|0))|0;
  }

  return {
    fib:fib
  };
}

var m = _WASMEXP_.instantiateModuleFromAsm(fib.toString());
var asmFib = m.fib;

var n = 38;
console.time("ASM:fib(" + n + ")");
var f = asmFib(n, global);
console.log(f);
console.timeEnd("ASM:fib(" + n + ")");

binary wasm:

https://gist.github.com/sidorares/90607f73b499f2ccb7dd908a080ebe5d

Problems:

• no objects or strings in output. The only possible way I see now: generate json representation on the heap and use JSON.parse. Might still be fast! ( JSON.parse is very fast and often surpass manual object creation in speed )
• quite a lot of work for a unknown performance gain

Start with lib/compile_text_parser.js and the linked WebAssembly examples, then review the binary wasm gist and Node's --expose-wasm behavior. Compare a wasm-based parser with the current userspace JIT approach, especially how results cross the no-objects-or-strings boundary. Done requires an integrated parser and evidence that its performance gain justifies the added work.