Oilpan: use transition types for remaining RefPtr<Document>s in dom/.

Source/core/timing/PerformanceResourceTiming.cpp

Index: Source/core/timing/PerformanceResourceTiming.cpp
diff --git a/Source/core/timing/PerformanceResourceTiming.cpp b/Source/core/timing/PerformanceResourceTiming.cpp
index 8648b4fcbefb0a9e65bbf215008bde6e916dcc14..32cacfe246a575aa7b61020040d1d64344d80ed3 100644
--- a/Source/core/timing/PerformanceResourceTiming.cpp
+++ b/Source/core/timing/PerformanceResourceTiming.cpp
@@ -191,4 +191,10 @@ double PerformanceResourceTiming::responseEnd() const
     return monotonicTimeToDocumentMilliseconds(m_requestingDocument.get(), m_finishTime);
 }
 
+void PerformanceResourceTiming::trace(Visitor* visitor)
+{
+    visitor->trace(m_requestingDocument);
+    PerformanceEntry::trace(visitor);
+}
+
 } // namespace WebCore