<!DOCTYPE html>
<html>
<body>
<div id="container">
    <form id="test"></form>
    <form id="test"></form>
    <input form="test">
</div>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
container.remove();
document.write(`This tests removing a subtree containing a form associated element with two form elements with matching ID.<br>
The test passses if WebKit doesn't hit a debug assertion.<br>
PASS.`);
</script>
</body>
</html>