Make TreeScopeEventContext have a RefPtr to TreeScope.rootNode to guard TreeScope.

Source/core/events/TreeScopeEventContext.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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 24 matching lines @@
 namespace blink {
 
 PassRefPtrWillBeRawPtr<StaticNodeList> TreeScopeEventContext::ensureEventPath(EventPath& path)
 {
     if (m_eventPath)
         return m_eventPath;
 
     WillBeHeapVector<RefPtrWillBeMember<Node>> nodes;
     nodes.reserveInitialCapacity(path.size());
     for (size_t i = 0; i < path.size(); ++i) {
-        TreeScope& treeScope = path[i].treeScopeEventContext().treeScope();
-        if (treeScope.rootNode().isShadowRoot() && toShadowRoot(treeScope).type() == ShadowRoot::AuthorShadowRoot)
+        Node& rootNode = path[i].treeScopeEventContext().rootNode();
+        if (rootNode.isShadowRoot() && toShadowRoot(rootNode).type() == ShadowRoot::AuthorShadowRoot)
             nodes.append(path[i].node());
         else if (path[i].treeScopeEventContext().isInclusiveAncestorOf(*this))
             nodes.append(path[i].node());
     }
     m_eventPath = StaticNodeList::adopt(nodes);
     return m_eventPath;
 }
 
 TouchEventContext* TreeScopeEventContext::ensureTouchEventContext()
 {
     if (!m_touchEventContext)
         m_touchEventContext = TouchEventContext::create();
     return m_touchEventContext.get();
 }
 
 PassRefPtrWillBeRawPtr<TreeScopeEventContext> TreeScopeEventContext::create(TreeScope& treeScope)
 {
     return adoptRefWillBeNoop(new TreeScopeEventContext(treeScope));
 }
 
 TreeScopeEventContext::TreeScopeEventContext(TreeScope& treeScope)
     : m_treeScope(treeScope)
+    , m_rootNode(treeScope.rootNode())
     , m_preOrder(-1)
     , m_postOrder(-1)
 {
 }
 
 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(TreeScopeEventContext)
 
 void TreeScopeEventContext::trace(Visitor* visitor)
 {
     visitor->trace(m_treeScope);
+    visitor->trace(m_rootNode);
     visitor->trace(m_target);
     visitor->trace(m_relatedTarget);
     visitor->trace(m_eventPath);
     visitor->trace(m_touchEventContext);
 #if ENABLE(OILPAN)
     visitor->trace(m_children);
 #endif
 }
 
 int TreeScopeEventContext::calculatePrePostOrderNumber(int orderNumber)
 {
     m_preOrder = orderNumber;
     for (size_t i = 0; i < m_children.size(); ++i)
         orderNumber = m_children[i]->calculatePrePostOrderNumber(orderNumber + 1);
     m_postOrder = orderNumber + 1;
     return orderNumber + 1;
 }
 
 }