Support tag names as invalidation set features.

Source/core/css/invalidation/DescendantInvalidationSet.cpp

 /*
  * Copyright (C) 2014 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 143 matching lines @@
 }
 
 void DescendantInvalidationSet::getIds(Vector<AtomicString>& ids) const
 {
     if (!m_ids)
         return;
     for (HashSet<AtomicString>::const_iterator it = m_ids->begin(); it != m_ids->end(); ++it)
         ids.append(*it);
 }
 
+void DescendantInvalidationSet::getTagNames(Vector<AtomicString>& tagNames) const
+{
+    if (!m_tagNames)
+        return;
+    for (HashSet<AtomicString>::const_iterator it = m_tagNames->begin(); it != m_tagNames->end(); ++it)
+        tagNames.append(*it);
+}
+
 void DescendantInvalidationSet::setWholeSubtreeInvalid()
 {
     if (m_allDescendantsMightBeInvalid)
         return;
 
     m_allDescendantsMightBeInvalid = true;
     m_classes = nullptr;
     m_ids = nullptr;
     m_tagNames = nullptr;
     m_attributes = nullptr;
 }
 
 } // namespace WebCore