Oilpan: fix Windows build after r187674.

Source/platform/heap/Visitor.h

Index: Source/platform/heap/Visitor.h
diff --git a/Source/platform/heap/Visitor.h b/Source/platform/heap/Visitor.h
index 3e9d21891861c322483c6dd58d7a454152b75d2e..dce9d8f9acecbd26be562597e4b731c828376206 100644
--- a/Source/platform/heap/Visitor.h
+++ b/Source/platform/heap/Visitor.h
@@ -63,8 +63,37 @@ class HeapObjectHeader;
 class InlinedGlobalMarkingVisitor;
 template<typename T> class Member;
 template<typename T> class WeakMember;
+template<typename ValueArg, size_t inlineCapacity> struct HeapListHashSetAllocator;
 class Visitor;
 
+} // namespace blink
+
+namespace WTF {
+
+template<typename ValueArg, typename Allocator> class ListHashSetNode;
+
+template<typename T>
+struct NeedsTracing<blink::Member<T>> {
+    static const bool value = true;
+};
+
+template<typename T>
+struct IsWeak<blink::WeakMember<T>> {
+    static const bool value = true;
+};
+
+template<typename T, size_t inlineCapacity>
+struct NeedsTracing<ListHashSetNode<T, blink::HeapListHashSetAllocator<T, inlineCapacity>> *> {
+    // All heap allocated node pointers need visiting to keep the nodes alive,
+    // regardless of whether they contain pointers to other heap allocated
+    // objects.
+    static const bool value = true;
+};
+
+} // namespace WTF
+
+namespace blink {
+
 template <typename T> struct IsGarbageCollectedType;
 #define STATIC_ASSERT_IS_GARBAGE_COLLECTED(T, ErrorMessage) \
     static_assert(IsGarbageCollectedType<T>::value, ErrorMessage)
@@ -180,7 +209,7 @@ public:
     static const bool value = true;
 };
 
-template <typename T, bool = HasInlinedTraceMethod<T>::value>
+template <typename T, bool needsTracing, bool = HasInlinedTraceMethod<T>::value>
 struct TraceCompatibilityAdaptor;
 
 // The TraceTrait is used to specify how to mark an object pointer and
@@ -196,13 +225,14 @@ struct TraceCompatibilityAdaptor;
 // that case the pointer has to be adjusted before marking.
 template<typename T>
 class TraceTrait {
+    static const bool needsTracing = WTF::NeedsTracing<T>::value || WTF::IsWeak<T>::value;
 public:
     // Default implementation of TraceTrait<T>::trace just statically
     // dispatches to the trace method of the class T.
     template<typename VisitorDispatcher>
     static void trace(VisitorDispatcher visitor, void* self)
     {
-        TraceCompatibilityAdaptor<T>::trace(visitor, static_cast<T*>(self));
+        TraceCompatibilityAdaptor<T, needsTracing>::trace(visitor, static_cast<T*>(self));
     }
 
     template<typename VisitorDispatcher>