Oilpan: have History on the heap by default.

Source/core/events/PopStateEvent.h

Index: Source/core/events/PopStateEvent.h
diff --git a/Source/core/events/PopStateEvent.h b/Source/core/events/PopStateEvent.h
index c3796e4760db1c94104dd7e6b1922239d524939e..32a314f32b3f00bf3592036f79beabbcab50419a 100644
--- a/Source/core/events/PopStateEvent.h
+++ b/Source/core/events/PopStateEvent.h
@@ -42,7 +42,7 @@ class PopStateEvent final : public Event {
 public:
     virtual ~PopStateEvent();
     static PassRefPtrWillBeRawPtr<PopStateEvent> create();
-    static PassRefPtrWillBeRawPtr<PopStateEvent> create(PassRefPtr<SerializedScriptValue>, PassRefPtrWillBeRawPtr<History>);
+    static PassRefPtrWillBeRawPtr<PopStateEvent> create(PassRefPtr<SerializedScriptValue>, History*);
     static PassRefPtrWillBeRawPtr<PopStateEvent> create(const AtomicString&, const PopStateEventInit&);
 
     SerializedScriptValue* serializedState() const { return m_serializedState.get(); }
@@ -60,10 +60,10 @@ public:
 private:
     PopStateEvent();
     PopStateEvent(const AtomicString&, const PopStateEventInit&);
-    PopStateEvent(PassRefPtr<SerializedScriptValue>, PassRefPtrWillBeRawPtr<History>);
+    PopStateEvent(PassRefPtr<SerializedScriptValue>, History*);
 
     RefPtr<SerializedScriptValue> m_serializedState;
-    RefPtrWillBeMember<History> m_history;
+    PersistentWillBeMember<History> m_history;
 };
 
 } // namespace blink