Add support for rel=next to Prerender in Blink.

Source/core/html/LinkRelAttribute.h

 /*
  * Copyright (C) 2011 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 34 matching lines @@
     LinkRelAttribute();
     explicit LinkRelAttribute(const String&);
 
     bool isStyleSheet() const { return m_isStyleSheet; }
     IconType iconType() const { return m_iconType; }
     bool isAlternate() const { return m_isAlternate; }
     bool isDNSPrefetch() const { return m_isDNSPrefetch; }
     bool isLinkPrefetch() const { return m_isLinkPrefetch; }
     bool isLinkSubresource() const { return m_isLinkSubresource; }
     bool isLinkPrerender() const { return m_isLinkPrerender; }
+    bool isLinkNext() const { return m_isLinkNext; }
     bool isImport() const { return m_isImport; }
 
 private:
     IconType m_iconType;
     bool m_isStyleSheet : 1;
     bool m_isAlternate : 1;
     bool m_isDNSPrefetch : 1;
     bool m_isLinkPrefetch : 1;
     bool m_isLinkSubresource : 1;
     bool m_isLinkPrerender : 1;
+    bool m_isLinkNext : 1;
     bool m_isImport : 1;
 };
 
 }
 
 #endif