Refactor how embedded pointers are visited.

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index 86850369a906029c2075c000df787009f72013ae..d54d8224956e6dcd6c83b376cd2d5550420f4cc6 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -315,6 +315,7 @@ class SlotsBuffer {
   }
 
   enum SlotType {
+    EMBEDDED_OBJECT_SLOT,
     RELOCATED_CODE_OBJECT,
     CODE_TARGET_SLOT,
     CODE_ENTRY_SLOT,
@@ -538,7 +539,7 @@ class MarkCompactCollector {
     }
   }
 
-  void RecordRelocSlot(RelocInfo* rinfo, Code* target);
+  void RecordRelocSlot(RelocInfo* rinfo, Object* target);
   void RecordCodeEntrySlot(Address slot, Code* target);
 
   INLINE(void RecordSlot(Object** anchor_slot, Object** slot, Object* object));