Tools/TestWebKitAPI/Tests/WebKitCocoa/image-controls.html

<!DOCTYPE html>
<html>
<head>
<script>
addEventListener("load", () => {
    if (!window.HTMLAttachmentElement)
        return;

    HTMLAttachmentElement.getAttachmentIdentifier(document.querySelector("img"));
});

function servicesControlButton()
{
    return internals.shadowRoot(document.querySelector("img")).getElementById("image-controls-button");
}

async function waitForAndClickImageControls()
{
    if (!window.internals)
        return;

    let button = null;
    do {
        await new Promise(requestAnimationFrame);
        button = servicesControlButton();
    } while (!button);
    button.click();
}
</script>
</head>
<body><img src="icon.png"></img></body>
</html>