Oilpan: Prepare to move SQLTransactionWrapper and CangeVersionWrapper to Oilpan heap.

Source/modules/webdatabase/DatabaseBackend.cpp

Index: Source/modules/webdatabase/DatabaseBackend.cpp
diff --git a/Source/modules/webdatabase/DatabaseBackend.cpp b/Source/modules/webdatabase/DatabaseBackend.cpp
index 556aa5b594a2260591dab16b7082b2f2a54eaa89..75f3b04ea198467ef395374d9a70aea80fa4b760 100644
--- a/Source/modules/webdatabase/DatabaseBackend.cpp
+++ b/Source/modules/webdatabase/DatabaseBackend.cpp
@@ -112,11 +112,11 @@ PassRefPtrWillBeRawPtr<SQLTransactionBackend> DatabaseBackend::runTransaction(Pa
     if (!m_isTransactionQueueEnabled)
         return nullptr;
 
-    RefPtr<SQLTransactionWrapper> wrapper;
+    RefPtrWillBeRawPtr<SQLTransactionWrapper> wrapper = nullptr;
     if (data)
         wrapper = ChangeVersionWrapper::create(data->oldVersion(), data->newVersion());
 
-    RefPtrWillBeRawPtr<SQLTransactionBackend> transactionBackend = SQLTransactionBackend::create(this, transaction, wrapper, readOnly);
+    RefPtrWillBeRawPtr<SQLTransactionBackend> transactionBackend = SQLTransactionBackend::create(this, transaction, wrapper.release(), readOnly);
     m_transactionQueue.append(transactionBackend);
     if (!m_transactionInProgress)
         scheduleTransaction();