Reintroduced dictionary that can use objects as keys.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 6b50f99cdad232648012734d976959b65a62c871..bf3ed278537c1df86f15d19cd474378c52045820 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -3192,39 +3192,7 @@ int v8::Object::GetIdentityHash() {
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::Object> hidden_props_obj(i::GetHiddenProperties(self, true));
-  if (!hidden_props_obj->IsJSObject()) {
-    // We failed to create hidden properties.  That's a detached
-    // global proxy.
-    ASSERT(hidden_props_obj->IsUndefined());
-    return 0;
-  }
-  i::Handle<i::JSObject> hidden_props =
-      i::Handle<i::JSObject>::cast(hidden_props_obj);
-  i::Handle<i::String> hash_symbol = isolate->factory()->identity_hash_symbol();
-  if (hidden_props->HasLocalProperty(*hash_symbol)) {
-    i::Handle<i::Object> hash = i::GetProperty(hidden_props, hash_symbol);
-    CHECK(!hash.is_null());
-    CHECK(hash->IsSmi());
-    return i::Smi::cast(*hash)->value();
-  }
-
-  int hash_value;
-  int attempts = 0;
-  do {
-    // Generate a random 32-bit hash value but limit range to fit
-    // within a smi.
-    hash_value = i::V8::Random(self->GetIsolate()) & i::Smi::kMaxValue;
-    attempts++;
-  } while (hash_value == 0 && attempts < 30);
-  hash_value = hash_value != 0 ? hash_value : 1;  // never return 0
-  CHECK(!i::SetLocalPropertyIgnoreAttributes(
-          hidden_props,
-          hash_symbol,
-          i::Handle<i::Object>(i::Smi::FromInt(hash_value)),
-          static_cast<PropertyAttributes>(None)).is_null());
-
-  return hash_value;
+  return i::GetIdentityHash(self)->value();
 }