By popular demand: Slightly more honest typing in ClearNonLiveMapTransitions

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 3636aa6fb5643e779679289d8b17e1b7c2ef50af..bda94f4febb609e91f64c3d79181e755782af895 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -2368,9 +2368,9 @@ void MarkCompactCollector::ClearNonLivePrototypeTransitions(Map* map) {
 void MarkCompactCollector::ClearNonLiveMapTransitions(Map* map,
                                                       MarkBit map_mark) {
   // Follow the chain of back pointers to find the prototype.
-  Map* real_prototype = map;
+  Object* real_prototype = map;
   while (real_prototype->IsMap()) {
-    real_prototype = reinterpret_cast<Map*>(real_prototype->prototype());
+    real_prototype = Map::cast(real_prototype)->prototype();
     ASSERT(real_prototype->IsHeapObject());
   }