Try running this:
Object.prototype.d = 4;
Now you'll get: 1
2
3
4 Object.prototype.d = 4;
Now you'll get: 1
2
3
4 Object.prototype.d = 4;
I'd be asking for trouble. Object.prototype.myDumbShim = function () { ... };
Chances are good that your code will be running in the same scope as one of these people's code eventually.