CORS: Handle error HTTP status code 4XX/5XX in preflight requests.

Source/core/loader/CrossOriginAccessControl.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 148 matching lines @@
         const String& accessControlCredentialsString = response.httpHeaderField(accessControlAllowCredentials);
         if (accessControlCredentialsString != "true") {
             errorDescription = "Credentials flag is true, but Access-Control-Allow-Credentials is not \"true\".";
             return false;
         }
     }
 
     return true;
 }
 
+bool passesPreflightStatusCheck(const ResourceResponse& response, String& errorDescription)
+{
+    if (response.httpStatusCode() < 200 || response.httpStatusCode() >= 400) {
+        errorDescription = "Invalid HTTP status code " + String::number(response.httpStatusCode());
+        return false;
+    }
+
+    return true;
+}
+
 void parseAccessControlExposeHeadersAllowList(const String& headerValue, HTTPHeaderSet& headerSet)
 {
     Vector<String> headers;
     headerValue.split(',', false, headers);
     for (unsigned headerCount = 0; headerCount < headers.size(); headerCount++) {
         String strippedHeader = headers[headerCount].stripWhiteSpace();
         if (!strippedHeader.isEmpty())
             headerSet.add(strippedHeader);
     }
 }
 
 } // namespace WebCore