Improve handling of CORS redirects for some resource loads.

LayoutTests/http/tests/security/script-crossorigin-redirect-credentials-expected.txt

+CONSOLE ERROR: Script from origin 'http://localhost:8000' has been blocked from loading by Cross-Origin Resource Sharing policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.
+CONSOLE ERROR: Script from origin 'http://127.0.0.1:8080' has been blocked from loading by Cross-Origin Resource Sharing policy: The 'Access-Control-Allow-Origin' header has a value 'http://127.0.0.1:8000' that is not equal to the supplied origin. Origin 'null' is therefore not allowed access.
+Testing the handling of CORS-enabled script fetch in the presence of 'credentialled' redirects.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS/FAIL descriptions are of the form, 'CORS request type': 'redirect CORS type' => 'resource'
+
+PASS: Anonymous request: credentialled => no-CORS script resource.
+PASS: Anonymous request: credentialled => anonymous CORS script resource.
+PASS: Credentialled request: credentialled => credentialled-CORS script resource (same origin)
+PASS: Credentialled request: credentialled => credentialled-CORS script resource (cross origin)
+PASS: Credentialled request: credentialled => anonymous-CORS script resource (cross origin)
+PASS successfullyParsed is true
+
+TEST COMPLETE
+