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

Source/wtf/Vector.h

Index: Source/wtf/Vector.h
diff --git a/Source/wtf/Vector.h b/Source/wtf/Vector.h
index 50e924d617283b71049a3e538872d106314e1f79..982c68912b935dbb594515eb43e6e10c12953a36 100644
--- a/Source/wtf/Vector.h
+++ b/Source/wtf/Vector.h
@@ -745,7 +745,7 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
 
         void reverse();
 
-        void trace(typename Allocator::Visitor*);
+        template<typename VisitorDispatcher> void trace(VisitorDispatcher);
 
     private:
         void expandCapacity(size_t newMinCapacity);
@@ -1210,14 +1210,15 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
     // 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 Vector<T, inlineCapacity, Allocator>::trace(typename Allocator::Visitor* visitor)
+    template<typename VisitorDispatcher>
+    void Vector<T, inlineCapacity, Allocator>::trace(VisitorDispatcher visitor)
     {
         ASSERT(Allocator::isGarbageCollected); // Garbage collector must be enabled.
         const T* bufferBegin = buffer();
         const T* bufferEnd = buffer() + size();
         if (ShouldBeTraced<VectorTraits<T> >::value) {
             for (const T* bufferEntry = bufferBegin; 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 (this->hasOutOfLineBuffer())
             Allocator::markNoTracing(visitor, buffer());