Reapply r10158: Distinguish weak references in heap snapshots, group GC roots.

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 201 matching lines @@
  public:
   enum Type {
     kContextVariable = 0,  // A variable from a function context.
     kElement = 1,          // An element of an array.
     kProperty = 2,         // A named object property.
     kInternal = 3,         // A link that can't be accessed from JS,
                            // thus, its name isn't a real property name
                            // (e.g. parts of a ConsString).
     kHidden = 4,           // A link that is needed for proper sizes
                            // calculation, but may be hidden from user.
-    kShortcut = 5          // A link that must not be followed during
+    kShortcut = 5,         // A link that must not be followed during
                            // sizes calculation.
+    kWeak = 6              // A weak reference (ignored by the GC).
   };
 
   /** Returns edge type (see HeapGraphEdge::Type). */
   Type GetType() const;
 
   /**
    * Returns edge name. This can be a variable name, an element index, or
    * a property name.
    */
   Handle<Value> GetName() const;
@@ skipping 265 matching lines @@
 };
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 
 
 #endif  // V8_V8_PROFILER_H_