Use SameValueZero for Map and Set

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 910c25200ee3ec808f632a107078702138ea5d76..80848f882bd5e38dd185a4d6d4f9bf0a474f4a67 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1511,6 +1511,12 @@ class Object {
   // to implement the Harmony "egal" function.
   bool SameValue(Object* other);
 
+  // Checks whether this object has the same value as the given one.
+  // +0 and -0 are treated equal. Everything else is the same as SameValue.
+  // This function is implemented according to ES6, section 7.2.4 and is used
+  // by ES6 Map and Set.
+  bool SameValueZero(Object* other);
+
   // Tries to convert an object to an array index.  Returns true and sets
   // the output parameter if it succeeds.
   inline bool ToArrayIndex(uint32_t* index);
@@ -4142,7 +4148,7 @@ class ObjectHashTable: public HashTable<ObjectHashTable,
 // insertion order. There are Map and Set interfaces (OrderedHashMap
 // and OrderedHashTable, below). It is meant to be used by JSMap/JSSet.
 //
-// Only Object* keys are supported, with Object::SameValue() used as the
+// Only Object* keys are supported, with Object::SameValueZero() used as the
 // equality operator and Object::GetHash() for the hash function.
 //
 // Based on the "Deterministic Hash Table" as described by Jason Orendorff at