Added <link rel=preconnect> crossorigin attribute

Source/platform/network/NetworkHints.cpp

 /*
  * Copyright (C) 2008 Collin Jackson  <collinj@webkit.org>
  * Copyright (C) 2013 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:
  * 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 20 matching lines @@
 #include "public/platform/WebPrescientNetworking.h"
 
 namespace blink {
 
 void prefetchDNS(const String& hostname)
 {
     if (WebPrescientNetworking* prescientNetworking = Platform::current()->prescientNetworking())
         prescientNetworking->prefetchDNS(hostname);
 }
 
-void preconnect(const KURL& url)
+void preconnect(const KURL& url, const CrossOriginAttributeValue crossOrigin)
 {
+    // TODO(yoav): Should send the crossOrigin data to the Chrome side.

[Mike West, 2015/05/11 12:53:35]

Why not define the new method in this patch and give it a default implementation
that forwards to the existing implementation? Then you'll have one less thing to
do in the patch where you remove the old implementation.

     if (WebPrescientNetworking* prescientNetworking = Platform::current()->prescientNetworking())
         prescientNetworking->preconnect(url);
 }
 
 } // namespace blink