JSTests/microbenchmarks/put-by-id-replace-and-transition.js

(function() {
    var o;
    var n = 1000000;
    for (var i = 0; i < n; ++i) {
        if (i & 1)
            o = {f: 1};
        else
            o = {f: 1, g: 2};
        o.g = i;
    }
    if (o.g != n - 1)
        throw "Error: bad value of o.g: " + o.g;
})();