Oilpan: remove RawPtr<> usage for WebNotification.

Source/web/WebNotification.cpp

Index: Source/web/WebNotification.cpp
diff --git a/Source/web/WebNotification.cpp b/Source/web/WebNotification.cpp
index 58386071a4b9c4c8edf4f4cb68d4a8c3c9026057..91cc927446786860a9fb1ac328aeecae7d14334e 100644
--- a/Source/web/WebNotification.cpp
+++ b/Source/web/WebNotification.cpp
@@ -114,12 +114,12 @@ void WebNotification::dispatchClickEvent()
     m_private->dispatchClickEvent();
 }
 
-WebNotification::WebNotification(const WTF::RawPtr<Notification>& notification)
+WebNotification::WebNotification(Notification* notification)
     : m_private(notification)
 {
 }
 
-WebNotification& WebNotification::operator=(const WTF::RawPtr<Notification>& notification)
+WebNotification& WebNotification::operator=(Notification* notification)
 {
     m_private = notification;
     return *this;