Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/fast/frames/resources/iframe-display-none-child.html 

<html>
    <head>
    </head>
    <body onload="alert('this comes from the child frame onload handler!')">
        <div id="text">This text comes from the hidden iframe</div>
    </body>
</html>