LayoutTests/http/tests/security/sandboxed-iframe-DENIED-modals.html

<script>
if (window.testRunner)
    testRunner.dumpAsText();
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<p>This test passes if opening modal dialogs is blocked and the corresponding calls return immediately with the expected values.</p>
<iframe sandbox="allow-scripts"
        src="data:text/html,<script>
            console.log('window.alert returned ' + alert('MESSAGE'));
            </script>"></iframe>
<iframe sandbox="allow-scripts"
        src="data:text/html,<script>
            console.log('window.confirm returned ' + confirm('MESSAGE?'));
            </script>"></iframe>
<iframe sandbox="allow-scripts"
        src="data:text/html,<script>
            console.log('window.prompt returned ' + prompt('MESSAGE:', 'DEFAULT'));
            </script>"></iframe>
<iframe sandbox="allow-scripts"
        src="data:text/html,<script>
            console.log('window.print returned ' + print());
            </script>"></iframe>
<iframe sandbox="allow-scripts"
        src="data:text/html,<script>
            console.log('document.execCommand returned ' + document.execCommand('print', true, null));
            </script>"></iframe>