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

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 3734 matching lines @@
         return;
     }
 
     KURL cookieURL = this->cookieURL();
     if (cookieURL.isEmpty())
         return;
 
     setCookies(this, cookieURL, value);
 }
 
-AtomicString Document::referrer() const
+const AtomicString& Document::referrer() const
 {
     if (loader())
         return loader()->request().httpReferrer();
     return nullAtom;
 }
 
 String Document::domain() const
 {
     return securityOrigin()->domain();
 }
@@ skipping 35 matching lines @@
     if (m_frame)
         m_frame->script().updateSecurityOrigin();
 }
 
 // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-lastmodified
 String Document::lastModified() const
 {
     DateComponents date;
     bool foundDate = false;
     if (m_frame) {
-        String httpLastModified;
-        if (DocumentLoader* documentLoader = loader())
-            httpLastModified = documentLoader->response().httpHeaderField("Last-Modified");
-        if (!httpLastModified.isEmpty()) {
-            date.setMillisecondsSinceEpochForDateTime(parseDate(httpLastModified));
-            foundDate = true;
+        if (DocumentLoader* documentLoader = loader()) {
+            const AtomicString& httpLastModified = documentLoader->response().httpHeaderField("Last-Modified");
+            if (!httpLastModified.isEmpty()) {
+                date.setMillisecondsSinceEpochForDateTime(parseDate(httpLastModified));
+                foundDate = true;
+            }
         }
     }
     // FIXME: If this document came from the file system, the HTML5
     // specificiation tells us to read the last modification date from the file
     // system.
     if (!foundDate)
         date.setMillisecondsSinceEpochForDateTime(currentTimeMS());
     return String::format("%02d/%02d/%04d %02d:%02d:%02d", date.month() + 1, date.monthDay(), date.fullYear(), date.hour(), date.minute(), date.second());
 }
 
@@ skipping 1405 matching lines @@
 }
 
 FastTextAutosizer* Document::fastTextAutosizer()
 {
     if (!m_fastTextAutosizer && RuntimeEnabledFeatures::fastTextAutosizingEnabled())
         m_fastTextAutosizer = FastTextAutosizer::create(this);
     return m_fastTextAutosizer.get();
 }
 
 } // namespace WebCore