Oilpan: Replace RefPtrs to Node and its subclasses in core/events/ with Oilpan transition types.

Source/core/events/MutationEvent.cpp

Index: Source/core/events/MutationEvent.cpp
diff --git a/Source/core/events/MutationEvent.cpp b/Source/core/events/MutationEvent.cpp
index d763e96ab53be8b5fcedfb63d9643c8a1fa4e7c2..4c78269f9d9ba70753409164987c063b2159d11b 100644
--- a/Source/core/events/MutationEvent.cpp
+++ b/Source/core/events/MutationEvent.cpp
@@ -31,7 +31,7 @@ MutationEvent::MutationEvent()
     ScriptWrappable::init(this);
 }
 
-MutationEvent::MutationEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtr<Node> relatedNode,
+MutationEvent::MutationEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<Node> relatedNode,
                              const String& prevValue, const String& newValue,
                              const String& attrName, unsigned short attrChange)
     : Event(type, canBubble, cancelable)
@@ -48,7 +48,7 @@ MutationEvent::~MutationEvent()
 {
 }
 
-void MutationEvent::initMutationEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtr<Node> relatedNode,
+void MutationEvent::initMutationEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<Node> relatedNode,
                                       const String& prevValue, const String& newValue,
                                       const String& attrName, unsigned short attrChange)
 {
@@ -71,6 +71,7 @@ const AtomicString& MutationEvent::interfaceName() const
 
 void MutationEvent::trace(Visitor* visitor)
 {
+    visitor->trace(m_relatedNode);
     Event::trace(visitor);
 }