Limit <link rel=preconnect> to the HTTP family

Source/core/loader/LinkLoader.cpp

 /*
  * 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 113 matching lines @@
         if (settings && settings->dnsPrefetchingEnabled() && href.isValid() && !href.isEmpty()) {
             if (settings->logDnsPrefetchAndPreconnect())
                 document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("DNS prefetch triggered for " + href.host())));
             prefetchDNS(href.host());
         }
     }
 }
 
 static void preconnectIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const CrossOriginAttributeValue crossOrigin)
 {
-    if (relAttribute.isPreconnect() && href.isValid()) {
+    if (relAttribute.isPreconnect() && href.isValid() && href.protocolIsInHTTPFamily()) {
         ASSERT(RuntimeEnabledFeatures::linkPreconnectEnabled());
         Settings* settings = document.settings();
         if (settings && settings->logDnsPrefetchAndPreconnect()) {
             document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("Preconnect triggered for " + href.host())));
             if (crossOrigin != CrossOriginAttributeNotSet) {
                 document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel,
                     String("Preconnect CORS setting is ") + String((crossOrigin == CrossOriginAttributeAnonymous) ? "anonymous" : "use-credentials")));
             }
         }
         preconnect(href, crossOrigin);
@@ skipping 109 matching lines @@
         m_prerender.clear();
     }
 }
 
 DEFINE_TRACE(LinkLoader)
 {
     visitor->trace(m_prerender);
 }
 
 }