[oilpan] Fix iterators over member collections to return Result<T>

Source/heap/Handle.h

Index: Source/heap/Handle.h
diff --git a/Source/heap/Handle.h b/Source/heap/Handle.h
index 63e44b360a5ebbf04442ff999e426fae246870e7..d8d0f5fae4377f30cb45e0a54212a96ad4104855 100644
--- a/Source/heap/Handle.h
+++ b/Source/heap/Handle.h
@@ -40,6 +40,12 @@
 #include <wtf/TypeTraits.h>
 #include <wtf/Vector.h>
 
+namespace WTF {
+
+template<typename A, typename B, typename C, typename D, typename E, typename F, typename G> class HashTableConstIterator;
+
+}
+
 namespace WebCore {
 
 // Forward declarations.
@@ -759,6 +765,22 @@ public:
     Handle<T> handle() const { return Handle<T>(releaseRaw()); }
 
 private:
+    template<typename U>
+    Result(const Member<U>* other)
+        : m_raw(other->raw())
+#ifndef NDEBUG
+        , m_doNotAllocate()
+#endif
+    {
+    }
+
+    template<typename U>
+    Result& operator=(const Member<U>* other)
+    {
+        COMPILE_ASSERT(!sizeof(T*), Result_should_never_be_assigned_to);
+        return *this;
+    }
+
     explicit Result(T* raw)
         : m_raw(raw)
 #ifndef NDEBUG
@@ -785,6 +807,7 @@ private:
     mutable NoAllocation m_doNotAllocate;
 #endif
 
+    template<typename U> friend void Visitor::visit(const class Result<U>&);
     template<typename U> friend class Persistent;
     template<typename U> friend class Handle;
     template<typename U> friend class Member;
@@ -810,6 +833,7 @@ private:
     template<typename U, typename V> friend bool operator!=(const Result<U>&, const V*);
     template<typename U, typename V> friend bool operator==(const U*, const Result<V>&);
     template<typename U, typename V> friend bool operator!=(const U*, const Result<V>&);
+    template<typename A, typename B, typename C, typename D, typename E, typename F, typename G> friend class WTF::HashTableConstIterator;
 };
 
 template<class T>
@@ -1353,6 +1377,12 @@ template<typename T> struct HashTraits<WebCore::Member<T> > : SimpleClassHashTra
     // the two types can be merged into PassInType.
     typedef const typename WebCore::Handle<T>& PeekInType;
     typedef const typename WebCore::Handle<T>& PassInType;
+    typedef WebCore::Result<T> IteratorGetType;
+    typedef WebCore::Result<T> IteratorConstGetType;
+    typedef WebCore::Result<T> IteratorReferenceType;
+    typedef WebCore::Result<T> IteratorConstReferenceType;
+    static IteratorReferenceType getToReferenceConversion(IteratorGetType x) { return x; }
+    static IteratorConstReferenceType getToReferenceConstConversion(IteratorConstGetType x) { return x; }
     // FIXME(oilpan): Similarly, there is no need for a distinction between
     // PeekType and PassOutType without reference counting.
     typedef typename WebCore::Result<T> PeekType;