[Fetch API] Pass web-platform fetch/api/cors/cors-preflight.html.

third_party/WebKit/Source/core/fetch/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 59 matching lines @@
     }
     filteredHeaders.push_back(header.key.lower());
   }
 
   // Sort header names lexicographically.
   std::sort(filteredHeaders.begin(), filteredHeaders.end(),
             WTF::codePointCompareLessThan);
   StringBuilder headerBuffer;
   for (const String& header : filteredHeaders) {
     if (!headerBuffer.isEmpty())
-      headerBuffer.append(", ");
+      headerBuffer.append(",");
     headerBuffer.append(header);
   }
 
   return AtomicString(headerBuffer.toString());
 }
 
 ResourceRequest createAccessControlPreflightRequest(
     const ResourceRequest& request,
     const SecurityOrigin* securityOrigin) {
   const KURL& requestURL = request.url();
@@ skipping 336 matching lines @@
     //
     // This is equivalent to the step 2 in
     // https://fetch.spec.whatwg.org/#http-network-or-cache-fetch
     if (options.credentialsRequested == ClientDidNotRequestCredentials)
       options.allowCredentials = DoNotAllowStoredCredentials;
   }
   return true;
 }
 
 }  // namespace blink