Simple non-incremental compaction by evacuation.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 05cd1ab89e87dcdaa1469c93df1ab0ec5334fe01..963197ea7ec98e641732f3c1b9ddf9914471abd6 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3751,7 +3751,6 @@ class Map: public HeapObject {
   //    1 + 2 * i: prototype
   //    2 + 2 * i: target map
   DECL_ACCESSORS(prototype_transitions, FixedArray)
-  inline FixedArray* unchecked_prototype_transitions();
 
   // Lookup in the map's instance descriptors and fill out the result
   // with the given holder if the name is found. The holder may be