Oilpan: Improve Oilpan support in EventContext and EventPath.

Source/core/events/TreeScopeEventContext.cpp

Index: Source/core/events/TreeScopeEventContext.cpp
diff --git a/Source/core/events/TreeScopeEventContext.cpp b/Source/core/events/TreeScopeEventContext.cpp
index fa73a071a7a030d563c5de12e9e30bd7ebc215d1..213dfd5aa21ef955749e3637f725ca5683c5ccc0 100644
--- a/Source/core/events/TreeScopeEventContext.cpp
+++ b/Source/core/events/TreeScopeEventContext.cpp
@@ -59,9 +59,9 @@ TouchEventContext* TreeScopeEventContext::ensureTouchEventContext()
     return m_touchEventContext.get();
 }
 
-PassRefPtr<TreeScopeEventContext> TreeScopeEventContext::create(TreeScope& treeScope)
+PassRefPtrWillBeRawPtr<TreeScopeEventContext> TreeScopeEventContext::create(TreeScope& treeScope)
 {
-    return adoptRef(new TreeScopeEventContext(treeScope));
+    return adoptRefWillBeNoop(new TreeScopeEventContext(treeScope));
 }
 
 TreeScopeEventContext::TreeScopeEventContext(TreeScope& treeScope)
@@ -71,8 +71,18 @@ TreeScopeEventContext::TreeScopeEventContext(TreeScope& treeScope)
 {
 }
 
-TreeScopeEventContext::~TreeScopeEventContext()
+DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(TreeScopeEventContext)
+
+void TreeScopeEventContext::trace(Visitor* visitor)
 {
+    visitor->trace(m_treeScope);
+    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)