src/third_party/mozjs-45/js/src/jit-test/tests/ion/bug911369.js

var a = [];
var count = 0;
a.valueOf = function() {
    ++count;
}
function f(a) {
    6 - a;
}

f(3);
for (var i=0; i<10; i++)
    f(a);

assertEq(count, 10);