Revert of Remove StringBuilder::appendLiteral.

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 90 matching lines @@
                 // Access-Control-Request-Headers header.
                 continue;
             }
             headers.append(header.key.lower());
         }
         // Sort header names lexicographically.
         std::sort(headers.begin(), headers.end(), WTF::codePointCompareLessThan);
         StringBuilder headerBuffer;
         for (const String& header : headers) {
             if (!headerBuffer.isEmpty())
-                headerBuffer.append(", ");
+                headerBuffer.appendLiteral(", ");
             headerBuffer.append(header);
         }
         preflightRequest.setHTTPHeaderField(HTTPNames::Access_Control_Request_Headers, AtomicString(headerBuffer.toString()));
     }
 
     return preflightRequest;
 }
 
 static bool isOriginSeparator(UChar ch)
 {
@@ skipping 204 matching lines @@
         newRequest.setHTTPOrigin(securityOrigin);
         // If the user didn't request credentials in the first place, update our
         // state so we neither request them nor expect they must be allowed.
         if (options.credentialsRequested == ClientDidNotRequestCredentials)
             options.allowCredentials = DoNotAllowStoredCredentials;
     }
     return true;
 }
 
 } // namespace blink