Have HashMap<KeyType, AtomicString>::get() return a const reference

Source/core/html/parser/XSSAuditor.cpp

 /*
  * Copyright (C) 2011 Adam Barth. All Rights Reserved.
  * Copyright (C) 2011 Daniel Bates (dbates@intudata.com).
  *
  * 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
@@ skipping 245 matching lines @@
 
     if (document->encoding().isValid())
         m_encoding = document->encoding();
 
     m_decodedURL = fullyDecodeString(m_documentURL.string(), m_encoding);
     if (m_decodedURL.find(isRequiredForInjection) == kNotFound)
         m_decodedURL = String();
 
     String httpBodyAsString;
     if (DocumentLoader* documentLoader = document->frame()->loader().documentLoader()) {
-        DEFINE_STATIC_LOCAL(String, XSSProtectionHeader, ("X-XSS-Protection"));
-        String headerValue = documentLoader->response().httpHeaderField(XSSProtectionHeader);
+        DEFINE_STATIC_LOCAL(const AtomicString, XSSProtectionHeader, ("X-XSS-Protection", AtomicString::ConstructFromLiteral));
+        const AtomicString& headerValue = documentLoader->response().httpHeaderField(XSSProtectionHeader);
         String errorDetails;
         unsigned errorPosition = 0;
         String reportURL;
         KURL xssProtectionReportURL;
 
         // Process the X-XSS-Protection header, then mix in the CSP header's value.
         ReflectedXSSDisposition xssProtectionHeader = parseXSSProtectionHeader(headerValue, errorDetails, errorPosition, reportURL);
         m_didSendValidXSSProtectionHeader = xssProtectionHeader != ReflectedXSSUnset && xssProtectionHeader != ReflectedXSSInvalid;
         if ((xssProtectionHeader == FilterReflectedXSS || xssProtectionHeader == BlockReflectedXSS) && !reportURL.isEmpty()) {
             xssProtectionReportURL = document->completeURL(reportURL);
@@ skipping 444 matching lines @@
 }
 
 bool XSSAuditor::isSafeToSendToAnotherThread() const
 {
     return m_documentURL.isSafeToSendToAnotherThread()
         && m_decodedURL.isSafeToSendToAnotherThread()
         && m_decodedHTTPBody.isSafeToSendToAnotherThread();
 }
 
 } // namespace WebCore