[HTML Imports] Implement "load" and "error" events.

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 270 matching lines @@
 }
 
 void HTMLLinkElement::dispatchPendingLoadEvents()
 {
     linkLoadEventSender().dispatchPendingEvents();
 }
 
 void HTMLLinkElement::dispatchPendingEvent(LinkEventSender* eventSender)
 {
     ASSERT_UNUSED(eventSender, eventSender == &linkLoadEventSender());
-    ASSERT(linkStyle());
-    if (linkStyle()->hasLoadedSheet())
+    ASSERT(m_link);
+    if (m_link->hasLoaded())
         linkLoaded();
     else
         linkLoadingErrored();
 }
 
+void HTMLLinkElement::scheduleEvent()
+{
+    linkLoadEventSender().dispatchEventSoon(this);
+}
+
 void HTMLLinkElement::startLoadingDynamicSheet()
 {
     ASSERT(linkStyle());
     linkStyle()->startLoadingDynamicSheet();
 }
 
 bool HTMLLinkElement::isURLAttribute(const Attribute& attribute) const
 {
     return attribute.name().localName() == hrefAttr || HTMLElement::isURLAttribute(attribute);
 }
@@ skipping 140 matching lines @@
         return true;
     }
     return false;
 }
 
 void LinkStyle::notifyLoadedSheetAndAllCriticalSubresources(bool errorOccurred)
 {
     if (m_firedLoad)
         return;
     m_loadedSheet = !errorOccurred;
-    linkLoadEventSender().dispatchEventSoon(m_owner);
+    if (m_owner)
+        m_owner->scheduleEvent();
     m_firedLoad = true;
 }
 
 void LinkStyle::startLoadingDynamicSheet()
 {
     ASSERT(m_pendingSheetType < Blocking);
     addPendingSheet(Blocking);
 }
 
 void LinkStyle::clearSheet()
@@ skipping 164 matching lines @@
 void LinkStyle::ownerRemoved()
 {
     if (m_sheet)
         clearSheet();
 
     if (styleSheetIsLoading())
         removePendingSheet(RemovePendingSheetNotifyLater);
 }
 
 } // namespace WebCore