Optimize clearing of map transitions.

src/heap/objects-visiting.h

Index: src/heap/objects-visiting.h
diff --git a/src/heap/objects-visiting.h b/src/heap/objects-visiting.h
index f0925a71c7fdeba2dce02d2c8629a4d227529d25..81fa9dd78e74cf1be79d847c8ab5c79177f15932 100644
--- a/src/heap/objects-visiting.h
+++ b/src/heap/objects-visiting.h
@@ -374,10 +374,8 @@ class StaticMarkingVisitor : public StaticVisitorBase {
   INLINE(static void VisitNativeContext(Map* map, HeapObject* object));
   INLINE(static void VisitBytecodeArray(Map* map, HeapObject* object));
 
-  // Mark pointers in a Map and its TransitionArray together, possibly
-  // treating transitions or back pointers weak.
+  // Mark pointers in a Map treating some elements of the descriptor array weak.
   static void MarkMapContents(Heap* heap, Map* map);
-  static void MarkTransitionArray(Heap* heap, TransitionArray* transitions);
 
   // Mark pointers in the optimized code map that should act as strong
   // references, possibly treating some entries weak.