Oilpan: move LiveNodeList collections to the heap.

Source/core/dom/NodeRareData.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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 40 matching lines @@
         it->value->invalidateCacheForAttribute(attrName);
 
     if (attrName)
         return;
 
     TagCollectionCacheNS::iterator tagCacheEnd = m_tagCollectionCacheNS.end();
     for (TagCollectionCacheNS::iterator it = m_tagCollectionCacheNS.begin(); it != tagCacheEnd; ++it)
         it->value->invalidateCache();
 }
 
+#if ENABLE(OILPAN)
+void NodeListsNodeData::clearWeakMembers(Visitor* visitor)
+{
+    if (m_owner && (m_childNodeList ? 1 : 0) + m_atomicNameCaches.size() + m_tagCollectionCacheNS.size() == 0) {

[Mads Ager (chromium), 2014/05/20 06:58:57]

When we make m_owner strong again we can simplify and not check for m_owner and
not clear m_owner. We just need to check if everything became empty and clear
the Member from the owner to this object. Then this object will die in the next
GC round.

This could delay things a bit but the cleanup will happen eventually. During the
GC that makes this empty, we might get this callback before the sets have been
cleared by weak processing. That would delay the cleanup by one GC cycle. Then
we clear out the pointer from the owner to this object. This object will die in
the next round of GC, so we could delay the removal by two GCs but it will
happen in the end. :)

+        m_owner->clearNodeLists();
+        m_owner.clear();
+    }
+}
+#endif
+
 void NodeRareData::traceAfterDispatch(Visitor* visitor)
 {
     visitor->trace(m_mutationObserverData);
+    visitor->trace(m_nodeLists);
 }
 
 void NodeRareData::trace(Visitor* visitor)
 {
     if (m_isElementRareData)
         static_cast<ElementRareData*>(this)->traceAfterDispatch(visitor);
     else
         traceAfterDispatch(visitor);
 }
 
 void NodeRareData::finalizeGarbageCollectedObject()
 {
     RELEASE_ASSERT(!renderer());
     if (m_isElementRareData)
         static_cast<ElementRareData*>(this)->~ElementRareData();
     else
         this->~NodeRareData();
 }
 
 // Ensure the 10 bits reserved for the m_connectedFrameCount cannot overflow
 COMPILE_ASSERT(Page::maxNumberOfFrames < (1 << NodeRareData::ConnectedFrameCountBits), Frame_limit_should_fit_in_rare_data_count);
 
 } // namespace WebCore