Remove Debug object from the user roots in heap profiler.

src/profile-generator.h

 // Copyright 2011 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 1003 matching lines @@
   void SetPropertyReference(HeapObject* parent_obj,
                             HeapEntry* parent,
                             String* reference_name,
                             Object* child,
                             const char* name_format_string = NULL,
                             int field_offset = -1);
   void SetPropertyShortcutReference(HeapObject* parent_obj,
                                     HeapEntry* parent,
                                     String* reference_name,
                                     Object* child);
-  void SetWindowReference(Object* window);
+  void SetUserGlobalReference(Object* window);
   void SetRootGcRootsReference();
   void SetGcRootsReference(VisitorSynchronization::SyncTag tag);
   void SetGcSubrootReference(
       VisitorSynchronization::SyncTag tag, bool is_weak, Object* child);
   void SetObjectName(HeapObject* object);
   void TagObject(Object* obj, const char* tag);
 
   HeapEntry* GetEntry(Object* obj);
 
   static inline HeapObject* GetNthGcSubrootObject(int delta);
@@ skipping 158 matching lines @@
 
   friend class HeapSnapshotJSONSerializerEnumerator;
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_