CONSOLE ERROR: Unsafe attempt to load URL http://localhost:8000/security/resources/captions-with-access-control-headers.php from frame with URL http://127.0.0.1:8000/security/text-track-crossorigin.html. Domains, protocols and ports must match. CONSOLE ERROR: Access to text track at 'http://localhost:8000/security/resources/captions-with-access-control-headers.php?count=0' from origin 'http://127.0.0.1:8000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. CONSOLE ERROR: Unsafe attempt to load URL http://localhost:8000/security/resources/captions-with-access-control-headers.php from frame with URL http://127.0.0.1:8000/security/text-track-crossorigin.html. Domains, protocols and ports must match. Tests loading cross-domain . Loading without Access-Control-Allow-Origin header, no "crossorigin" attribute on