Test <img crossorigin> handling of 401 responses.

LayoutTests/http/tests/security/img-crossorigin-no-credentials-prompt-expected.txt

+CONSOLE ERROR: Image 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 'http://127.0.0.1:8000' is therefore not allowed access. The response had HTTP status code 401.
+CONSOLE ERROR: Image 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 'http://127.0.0.1:8000' is therefore not allowed access. The response had HTTP status code 401.
+No credentials should be prompted for on seeing a 401 for <img crossorigin>.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS Non-CORS image resource failed to load
+PASS Non-CORS image resource failed to load
+PASS successfullyParsed is true
+
+TEST COMPLETE
+