Introduce first approximation of constructor heap profile for JS objects.

src/zone.h

Index: src/zone.h
diff --git a/src/zone.h b/src/zone.h
index a8b26e9fd27a93e2c9edd719f836dfa98f761a60..cdbab3282130834bd961133fa9fbd312f5e4f65c 100644
--- a/src/zone.h
+++ b/src/zone.h
@@ -204,6 +204,108 @@ class ZoneScope BASE_EMBEDDED {
 };
 
 
+template <typename Node, class Callback>
+static void DoForEach(Node* node, Callback* callback);
+
+
+// A zone splay tree.  The config type parameter encapsulates the
+// different configurations of a concrete splay tree:
+//
+//   typedef Key: the key type
+//   typedef Value: the value type
+//   static const kNoKey: the dummy key used when no key is set
+//   static const kNoValue: the dummy value used to initialize nodes
+//   int (Compare)(Key& a, Key& b) -> {-1, 0, 1}: comparison function
+//
+template <typename Config>
+class ZoneSplayTree : public ZoneObject {
+ public:
+  typedef typename Config::Key Key;
+  typedef typename Config::Value Value;
+
+  class Locator;
+
+  ZoneSplayTree() : root_(NULL) { }
+
+  // Inserts the given key in this tree with the given value.  Returns
+  // true if a node was inserted, otherwise false.  If found the locator
+  // is enabled and provides access to the mapping for the key.
+  bool Insert(const Key& key, Locator* locator);
+
+  // Looks up the key in this tree and returns true if it was found,
+  // otherwise false.  If the node is found the locator is enabled and
+  // provides access to the mapping for the key.
+  bool Find(const Key& key, Locator* locator);
+
+  // Finds the mapping with the greatest key less than or equal to the
+  // given key.
+  bool FindGreatestLessThan(const Key& key, Locator* locator);
+
+  // Find the mapping with the greatest key in this tree.
+  bool FindGreatest(Locator* locator);
+
+  // Finds the mapping with the least key greater than or equal to the
+  // given key.
+  bool FindLeastGreaterThan(const Key& key, Locator* locator);
+
+  // Find the mapping with the least key in this tree.
+  bool FindLeast(Locator* locator);
+
+  // Remove the node with the given key from the tree.
+  bool Remove(const Key& key);
+
+  bool is_empty() { return root_ == NULL; }
+
+  // Perform the splay operation for the given key. Moves the node with
+  // the given key to the top of the tree.  If no node has the given
+  // key, the last node on the search path is moved to the top of the
+  // tree.
+  void Splay(const Key& key);
+
+  class Node : public ZoneObject {
+   public:
+    Node(const Key& key, const Value& value)
+        : key_(key),
+          value_(value),
+          left_(NULL),
+          right_(NULL) { }
+    Key key() { return key_; }
+    Value value() { return value_; }
+    Node* left() { return left_; }
+    Node* right() { return right_; }
+   private:
+    friend class ZoneSplayTree;
+    friend class Locator;
+    Key key_;
+    Value value_;
+    Node* left_;
+    Node* right_;
+  };
+
+  // A locator provides access to a node in the tree without actually
+  // exposing the node.
+  class Locator {
+   public:
+    explicit Locator(Node* node) : node_(node) { }
+    Locator() : node_(NULL) { }
+    const Key& key() { return node_->key_; }
+    Value& value() { return node_->value_; }
+    void set_value(const Value& value) { node_->value_ = value; }
+    inline void bind(Node* node) { node_ = node; }
+   private:
+    Node* node_;
+  };
+
+  template <class Callback>
+  void ForEach(Callback* c) {
+    DoForEach<typename ZoneSplayTree<Config>::Node, Callback>(root_, c);
+  }
+
+ private:
+  Node* root_;
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_ZONE_H_