Reland: Templatize visitor arguments for TraceTrait mark and trace methods.

Source/wtf/Deque.h

Index: Source/wtf/Deque.h
diff --git a/Source/wtf/Deque.h b/Source/wtf/Deque.h
index 0031c549cc04e3f478240663d046b00313fa9ab5..e853478df4a42148558e1cad51d6b2fd22939746 100644
--- a/Source/wtf/Deque.h
+++ b/Source/wtf/Deque.h
@@ -112,7 +112,7 @@ namespace WTF {
         template<typename Predicate>
         iterator findIf(Predicate&);
 
-        void trace(typename Allocator::Visitor*);
+        template<typename VisitorDispatcher> void trace(VisitorDispatcher);
 
     private:
         friend class DequeIteratorBase<T, inlineCapacity, Allocator>;
@@ -528,7 +528,8 @@ namespace WTF {
     // This is only called if the allocator is a HeapAllocator. It is used when
     // visiting during a tracing GC.
     template<typename T, size_t inlineCapacity, typename Allocator>
-    void Deque<T, inlineCapacity, Allocator>::trace(typename Allocator::Visitor* visitor)
+    template<typename VisitorDispatcher>
+    void Deque<T, inlineCapacity, Allocator>::trace(VisitorDispatcher visitor)
     {
         ASSERT(Allocator::isGarbageCollected); // Garbage collector must be enabled.
         const T* bufferBegin = m_buffer.buffer();
@@ -536,13 +537,13 @@ namespace WTF {
         if (ShouldBeTraced<VectorTraits<T> >::value) {
             if (m_start <= m_end) {
                 for (const T* bufferEntry = bufferBegin + m_start; bufferEntry != end; bufferEntry++)
-                    Allocator::template trace<T, VectorTraits<T> >(visitor, *const_cast<T*>(bufferEntry));
+                    Allocator::template trace<VisitorDispatcher, T, VectorTraits<T> >(visitor, *const_cast<T*>(bufferEntry));
             } else {
                 for (const T* bufferEntry = bufferBegin; bufferEntry != end; bufferEntry++)
-                    Allocator::template trace<T, VectorTraits<T> >(visitor, *const_cast<T*>(bufferEntry));
+                    Allocator::template trace<VisitorDispatcher, T, VectorTraits<T> >(visitor, *const_cast<T*>(bufferEntry));
                 const T* bufferEnd = m_buffer.buffer() + m_buffer.capacity();
                 for (const T* bufferEntry = bufferBegin + m_start; bufferEntry != bufferEnd; bufferEntry++)
-                    Allocator::template trace<T, VectorTraits<T> >(visitor, *const_cast<T*>(bufferEntry));
+                    Allocator::template trace<VisitorDispatcher, T, VectorTraits<T> >(visitor, *const_cast<T*>(bufferEntry));
             }
         }
         if (m_buffer.hasOutOfLineBuffer())