TraversableMap only dependent on DescriptorArray

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index e9dfe6ca55b94b8a923137b3cdfbcd47355ae79e..b6462dd78770e318d70c97187ea0ce97a914961d 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2588,6 +2588,8 @@ class DescriptorArray: public FixedArray {
   static const int kMaxNumberOfDescriptors = 1024 + 512;
 
  private:
+  friend class IntrusiveMapTransitionIterator;
+
   // An entry in a DescriptorArray, represented as an (array, index) pair.
   class Entry {
    public:
@@ -2626,6 +2628,7 @@ class DescriptorArray: public FixedArray {
   FixedArray* GetContentArray() {
     return FixedArray::cast(get(kContentArrayIndex));
   }
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(DescriptorArray);
 };