Add initial link preload support

Source/core/html/HTMLLinkElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 154 matching lines @@
 void HTMLLinkElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     if (name == relAttr) {
         m_relAttribute = LinkRelAttribute(value);
         process();
     } else if (name == hrefAttr) {
         process();
     } else if (name == typeAttr) {
         m_type = value;
         process();
+    } else if (name == asAttr) {
+        m_as = value;
+        process();
     } else if (name == sizesAttr) {
         m_sizes->setValue(value);
         parseSizesAttribute(value, m_iconSizes);
         process();
     } else if (name == mediaAttr) {
         m_media = value.lower();
         process();
     } else if (name == disabledAttr) {
         if (LinkStyle* link = linkStyle())
             link->setDisabledState(!value.isNull());
     } else {
         if (name == titleAttr) {
             if (LinkStyle* link = linkStyle())
                 link->setSheetTitle(value);
         }
 
         HTMLElement::parseAttribute(name, value);
     }
 }
 
 bool HTMLLinkElement::shouldLoadLink()
 {
     return inDocument();
 }
 
-bool HTMLLinkElement::loadLink(const String& type, const KURL& url)
+bool HTMLLinkElement::loadLink(const String& type, const String& as, const KURL& url)
 {
-    return m_linkLoader.loadLink(m_relAttribute, fastGetAttribute(HTMLNames::crossoriginAttr), type, url, document());
+    return m_linkLoader.loadLink(m_relAttribute, fastGetAttribute(HTMLNames::crossoriginAttr), type, as, url, document());
 }
 
 LinkResource* HTMLLinkElement::linkResourceToProcess()
 {
     bool visible = inDocument() && !m_isInShadowTree;
     if (!visible) {
         ASSERT(!linkStyle() || !linkStyle()->hasSheet());
         return nullptr;
     }
 
@@ skipping 470 matching lines @@
         // Only origins that are script accessible to it may access the stylesheet's rules.
         sheet->setAllowRuleAccessFromOrigin(m_owner->document().securityOrigin());
     }
     m_fetchFollowingCORS = false;
 }
 
 void LinkStyle::process()
 {
     ASSERT(m_owner->shouldProcessStyle());
     String type = m_owner->typeValue().lower();
+    String as = m_owner->asValue().lower();
     LinkRequestBuilder builder(m_owner);
 
     if (m_owner->relAttribute().iconType() != InvalidIcon && builder.url().isValid() && !builder.url().isEmpty()) {
         if (!m_owner->shouldLoadLink())
             return;
         if (!document().securityOrigin()->canDisplay(builder.url()))
             return;
         if (!document().contentSecurityPolicy()->allowImageFromSource(builder.url()))
             return;
         if (document().frame() && document().frame()->loader().client())
             document().frame()->loader().client()->dispatchDidChangeIcons(m_owner->relAttribute().iconType());
     }
 
-    if (!m_owner->loadLink(type, builder.url()))
+    if (!m_owner->loadLink(type, as, builder.url()))
         return;
 
     if ((m_disabledState != Disabled) && (m_owner->relAttribute().isStyleSheet() || m_owner->relAttribute().isTransitionExitingStylesheet())
         && shouldLoadResource() && builder.url().isValid()) {
 
         if (resource()) {
             removePendingSheet();
             clearResource();
         }
 
@@ skipping 54 matching lines @@
         removePendingSheet();
 }
 
 DEFINE_TRACE(LinkStyle)
 {
     visitor->trace(m_sheet);
     LinkResource::trace(visitor);
 }
 
 } // namespace blink