chromium/third_party/blink/web_tests/fast/js/pic/get-set-proxy-object.html

<p>
This page tests cached get and set through a proxy object. If the test passes,
you'll see a PASS message below.
</p>

<pre id="console"></pre>

<script>
if (window.testRunner)
    testRunner.dumpAsText();

function log(s)
{
    if (this.document)
        document.getElementById("console").appendChild(document.createTextNode(s));
    else
        print(s);
}

window.x = 1;
for (var i = 0; i < 3; ++i)
    window.x += 1;
    
log("PASS: You didn't crash.\n");
</script>