JSTests/microbenchmarks/object-assign-int32-source.js

let o = { "0": 1, "1": 2, "2": 3, "3": 4, "4": 5, "5": 6, "6": 7, "7": 8, "8": 9, };
for (let i = 0; i < 1e4; i++) {
    Object.assign({}, o);
    Object.assign({ "3": -1 }, o);
}