Adding Link header support for dns-prefetch

Source/core/testing/InternalSettings.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 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.
@@ skipping 456 matching lines @@
         settings()->setImageAnimationPolicy(ImageAnimationPolicyNoAnimation);
     else
         exceptionState.throwDOMException(SyntaxError, "The image animation policy provided ('" + policy + "') is invalid.");
 }
 
 void InternalSettings::setScrollTopLeftInteropEnabled(bool enabled)
 {
     RuntimeEnabledFeatures::setScrollTopLeftInteropEnabled(enabled);
 }
 
+void InternalSettings::setLinkHeaderEnabled(bool enabled)
+{
+    RuntimeEnabledFeatures::setLinkHeaderEnabled(enabled);
+}
+
 void InternalSettings::setDnsPrefetchLogging(bool enabled, ExceptionState& exceptionState)
 {
     InternalSettingsGuardForSettings();
     settings()->setLogDnsPrefetchAndPreconnect(enabled);
 }
 
 }