DescriptorArray::CopyFrom should always drop transitions for CALLBACKS.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index ef22af87178265704d961337f6dafc0af2d16034..1e49f0733f12af230cca895f8f3d04b7bc44ffc9 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2434,12 +2434,18 @@ class DescriptorArray: public FixedArray {
                   Descriptor* desc,
                   const WhitenessWitness&);
 
-  // Transfer complete descriptor from another descriptor array to
-  // this one.
-  inline void CopyFrom(int index,
-                       DescriptorArray* src,
+  // Transfer complete descriptor from src descriptor array to dst, dropping map
+  // transitions in CALLBACKS.
+  static void CopyFrom(Handle<DescriptorArray> dst,
+                       int dst_index,
+                       Handle<DescriptorArray> src,
                        int src_index,
-                       const WhitenessWitness&);
+                       const WhitenessWitness& witness);
+
+  MUST_USE_RESULT MaybeObject* CopyFrom(int dst_index,

[Michael Starzinger, 2012/02/13 14:04:17]

Could you add a similar comment like above to this function? It really helps
because most editors have the ability to quickly display those comments.

+                                        DescriptorArray* src,
+                                        int src_index,
+                                        const WhitenessWitness&);
 
   // Copy the descriptor array, insert a new descriptor and optionally
   // remove map transitions.  If the descriptor is already present, it is
@@ -7782,6 +7788,8 @@ class AccessorPair: public Struct {
 
   static inline AccessorPair* cast(Object* obj);
 
+  MaybeObject* CopyWithoutTransitions();

[Michael Starzinger, 2012/02/13 14:10:25]

This needs a MUST_USE_RESULT.

+
 #ifdef OBJECT_PRINT
   void AccessorPairPrint(FILE* out = stdout);
 #endif