I'd like to introduce kSynthetic type of nodes for Heap Profiler.

include/v8-profiler.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 237 matching lines @@
  public:
   enum Type {
     kHidden = 0,      // Hidden node, may be filtered when shown to user.
     kArray = 1,       // An array of elements.
     kString = 2,      // A string.
     kObject = 3,      // A JS object (except for arrays and strings).
     kCode = 4,        // Compiled code.
     kClosure = 5,     // Function closure.
     kRegExp = 6,      // RegExp.
     kHeapNumber = 7,  // Number stored in the heap.
-    kNative = 8       // Native object (not from V8 heap).
+    kNative = 8,      // Native object (not from V8 heap).
+    kSynthetic = 9    // Synthetic object, usualy used for grouping
+                      // snapshot items together.
   };
 
   /** Returns node type (see HeapGraphNode::Type). */
   Type GetType() const;
 
   /**
    * Returns node name. Depending on node's type this can be the name
    * of the constructor (for objects), the name of the function (for
    * closures), string value, or an empty string (for compiled code).
    */
@@ skipping 242 matching lines @@
 };
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 
 
 #endif  // V8_V8_PROFILER_H_