LayoutTests/http/tests/security/contentSecurityPolicy/frame-src-about-blank-allowed-by-scheme.html

<script>
if (window.testRunner)
    testRunner.dumpAsText();
</script>
<meta http-equiv="Content-Security-Policy" content="frame-src about:">
This iframe should not be blocked by Content-Security-Policy:
<iframe src="about:blank"></iframe>