Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/shadow/ElementShadow.cpp

 /*
  * Copyright (C) 2012 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.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 117 matching lines @@
 }
 
 ElementShadow::ElementShadow()
     : m_needsDistributionRecalc(false)
     , m_needsSelectFeatureSet(false)
 {
 }
 
 ElementShadow::~ElementShadow()
 {
+#if !ENABLE(OILPAN)
     removeDetachedShadowRoots();
+#endif
 }
 
 ShadowRoot& ElementShadow::addShadowRoot(Element& shadowHost, ShadowRoot::ShadowRootType type)
 {
     RefPtr<ShadowRoot> shadowRoot = ShadowRoot::create(shadowHost.document(), type);
 
     if (type == ShadowRoot::AuthorShadowRoot && (!youngestShadowRoot() || youngestShadowRoot()->type() == ShadowRoot::UserAgentShadowRoot))
         shadowHost.willAddFirstAuthorShadowRoot();
 
     for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot())
@@ skipping 194 matching lines @@
 }
 
 void ElementShadow::clearDistribution()
 {
     m_nodeToInsertionPoints.clear();
 
     for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot())
         root->setShadowInsertionPointOfYoungerShadowRoot(nullptr);
 }
 
+void ElementShadow::trace(Visitor* visitor)
+{
+    visitor->mark(m_shadowRoots.head());

[sof, 2014/05/05 11:27:48]

nit: you prefer to use mark() on raw pointers instead of trace()? Or is there
something else going on?

[Mads Ager (chromium), 2014/05/05 11:35:54]

Oops. Nothing special going on here. In the old days trace was called mark and
old habits die hard. ;-)

Changed to trace.

+}
+
 } // namespace