chromium/src/third_party/blink/web_tests/fast/events/option-tab.html

<p>This tests that option-tab moves you from a text field to a link, but plain old tab does not.</p>
<p>Note: Option is the Mac name for what other platforms call Alt.</p>
<input id="textField" type=text> <a onfocus="window.linkFocused = true" href="http://www.apple.com">link</a>
<input id="searchField" type=search> <a onfocus="window.linkFocused = true" href="http://www.apple.com">link</a>
<pre id="console">
</pre>
<script>

if (window.testRunner)
    testRunner.dumpAsText();

function test(fieldId)
{
    window.linkFocused = false;
    document.getElementById(fieldId).focus();

    if (window.eventSender)
        eventSender.keyDown('\u0009', ["altKey"]);

    if (window.linkFocused)
        document.getElementById("console").innerHTML += "SUCCESS: Option-tab did tab to the link (" + fieldId + ").\n";
    else
        document.getElementById("console").innerHTML += "FAIL: Option-tab did not tab to the link (" + fieldId + ").\n";

    window.linkFocused = false;
    document.getElementById(fieldId).focus();

    if (window.eventSender)
        eventSender.keyDown('\u0009', []);

    if (window.linkFocused)
        document.getElementById("console").innerHTML += "FAIL: Plain old tab did tab to the link (" + fieldId + ").\n";
    else
        document.getElementById("console").innerHTML += "SUCCESS: Plain old tab did not tab to the link (" + fieldId + ").\n";
}

test("textField");
test("searchField");

</script>