CONSOLE WARNING: line 8: Mixed Content: The page at 'https://127.0.0.1:8443/security/mixedContent/resources/frame-with-redirect-http-to-https-frame.html' was loaded over HTTPS, but requested an insecure resource 'http://example.test:8080/security/resources/redir.php?url=https://127.0.0.1:8443/security/mixedContent/resources/boring.html'. This content should also be served over HTTPS.
This test opens a window that loads an insecure iframe (via a tricky redirect). We should trigger a mixed content callback because the main frame in the window is HTTPS but is running content that can be controlled by an active network attacker.