Oilpan: move HistoryItem to the heap.

Source/web/WebHistoryItem.cpp

Index: Source/web/WebHistoryItem.cpp
diff --git a/Source/web/WebHistoryItem.cpp b/Source/web/WebHistoryItem.cpp
index 9e1c984581b4041e1010383eb3834c8e35018424..99623e7d00484eda86aa7858e2f1cd466313f97b 100644
--- a/Source/web/WebHistoryItem.cpp
+++ b/Source/web/WebHistoryItem.cpp
@@ -220,18 +220,18 @@ WebVector<WebString> WebHistoryItem::getReferencedFilePaths() const
     return results;
 }
 
-WebHistoryItem::WebHistoryItem(const PassRefPtr<HistoryItem>& item)
+WebHistoryItem::WebHistoryItem(const PassRefPtrWillBeRawPtr<HistoryItem>& item)
     : m_private(item)
 {
 }
 
-WebHistoryItem& WebHistoryItem::operator=(const PassRefPtr<HistoryItem>& item)
+WebHistoryItem& WebHistoryItem::operator=(const PassRefPtrWillBeRawPtr<HistoryItem>& item)
 {
     m_private = item;
     return *this;
 }
 
-WebHistoryItem::operator PassRefPtr<HistoryItem>() const
+WebHistoryItem::operator PassRefPtrWillBeRawPtr<HistoryItem>() const
 {
     return m_private.get();
 }