blabla

gistfile1.txt

so well

var f = function () {};
var bound = f.bind({});

(new bound) instanceof bound;

V = new bound;

bound[[HasInstance]](V);

/* inside 15.3.4.5.3 [[HasInstance]] (V) */
if (!bound[[Target]))
  throw;
target = bound[[Target]]
target[[HasInstance]](V)

/* target is just |f| */

/* at this point this is the same as (new bound) instanceof f */
/* 15.3.5.3 [[HasInstance]] (V) */
if (!IsObject(V))
  throw;
prototype = target.prototype;
do {
  V = V.__proto__; /* V proto is going to be f.prototype, because (new bound) is about the same as (new f)
  if (V === null)
    return false;

  if (V === prototype)
    return true; /* yaay ! */
} while (true);

Well crap, you guys are right. Here is the V8 bug report and explanation by Luke that made it click for me :D