Cleanup Blink side preconnect calls

public/platform/WebPrescientNetworking.h

 /*
  * 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:
  *
  *     * 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 27 matching lines @@
 namespace blink {
 
 class WebPrescientNetworking {
 public:
     virtual ~WebPrescientNetworking() { }
 
     // When a page navigation is speculated, DNS prefetch is triggered to hide
     // the host resolution latency.
     virtual void prefetchDNS(const WebString& hostname) { }
 
-    virtual void preconnect(const WebURL& url) { }
-
     virtual void preconnect(const WebURL& url, const bool allowCredentials) { }
 };
 
 } // namespace blink
 
 #endif // WebPrescientNetworking_h