chromium/third_party/blink/manual_tests/inspector/debugger-pause-during-load.html

<script>
debugger; // You should see this code and execution line in the Scripts panel.
</script>
<p>Test for <a href="https://bugs.webkit.org/show_bug.cgi?id=19053">Bug 19053: Source code not visible when script is paused before onload fires</a>.</p>
<p>To test, open the Inspector and start a debugging session. You should see this file and execution line in the Scripts panel.</p>