LayoutTests/fast/forms/validation-message-user-modify.html

<!DOCTYPE html>
<html>
<head>
<style>
::-webkit-validation-bubble,
::-webkit-validation-bubble-message,
::-webkit-validation-bubble-text-block,
::-webkit-validation-bubble-heading,
::-webkit-validation-bubble-arrow,
::-webkit-validation-bubble-arrow-clipper
{
    -webkit-user-modify: read-write;
}
</style>
</head>
<body>
<script src="../../resources/js-test-pre.js"></script>

<p>The inner element of validation should not be modifiable.</p>

<div id="container">
    <form action="validation-user-modify.html">
        <input type="checkbox" id="checkbox" required>
        <input type="submit" id="submit">
    </form>
</div>
<pre id="console"></pre>

<script>
jsTestIsAsync = true;

submit.click();

var renderTreeBeforeEditing;
var renderTreeAfterEditing;

setTimeout(function() {
    renderTreeBeforeEditing = internals.elementRenderTreeAsText(document.documentElement);

    for (var i = -20; i < 50; i += 10) {
        eventSender.mouseMoveTo(checkbox.offsetLeft + 20, checkbox.offsetTop + checkbox.offsetHeight + i);
        eventSender.mouseDown();
        eventSender.mouseUp();
        eventSender.keyDown('delete');
    }

    renderTreeAfterEditing = internals.elementRenderTreeAsText(document.documentElement);
    shouldBe("renderTreeAfterEditing", "renderTreeBeforeEditing");

    finishJSTest();                          
}, 0);

var successfullyParsed = true;
</script>
<script src="../../resources/js-test-post.js"></script>
</body>
</html>