src/third_party/mozjs-45/js/src/jit-test/tests/jaeger/bug639808.js

function f() {
    var x = 1.23;
    var y = [].length;
    x = ++y;
    y - 1;
}
f();

function g(q) {
    var x = 1.23;
    var y = [].length;
    x = ++y;
    if (q)
      assertEq(y + 5, 6);
}
g(1);