Fix Mac warnings

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/132263002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18522 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/list.h

@@ -205,7 +205,7 @@ size_t GetMemoryUsedByList(const List<T, P>& list) {
 
 class Map;
 template<class> class TypeImpl;
-class HeapTypeConfig;
+struct HeapTypeConfig;
 typedef TypeImpl<HeapTypeConfig> Type;
 class Code;
 template<typename T> class Handle;

src/objects.h

@@ -883,7 +883,7 @@ class ObjectVisitor;
 class StringStream;
 // We cannot just say "class Type;" if it is created from a template... =8-?
 template<class> class TypeImpl;
-class HeapTypeConfig;
+struct HeapTypeConfig;
 typedef TypeImpl<HeapTypeConfig> Type;
 
 

src/property-details.h

@@ -59,7 +59,7 @@ namespace internal {
 
 class Smi;
 template<class> class TypeImpl;
-class HeapTypeConfig;
+struct HeapTypeConfig;
 typedef TypeImpl<HeapTypeConfig> Type;
 class TypeInfo;