Added dictionary that can use objects as keys.

src/handles.cc

Index: src/handles.cc
diff --git a/src/handles.cc b/src/handles.cc
index d8cc742576e2a7550a27c5d4bace45e14bc60528..d9e4e0b492c3c357f608daef4a42d64892fc3a0b 100644
--- a/src/handles.cc
+++ b/src/handles.cc
@@ -427,38 +427,14 @@ Handle<Object> GetHiddenProperties(Handle<JSObject> obj,
   Object* holder = obj->BypassGlobalProxy();
   if (holder->IsUndefined()) return isolate->factory()->undefined_value();
   obj = Handle<JSObject>(JSObject::cast(holder), isolate);
+  CALL_HEAP_FUNCTION(isolate,
+                     obj->GetHiddenProperties(create_if_needed),
+                     Object);
+}
 
-  if (obj->HasFastProperties()) {
-    // If the object has fast properties, check whether the first slot
-    // in the descriptor array matches the hidden symbol. Since the
-    // hidden symbols hash code is zero (and no other string has hash
-    // code zero) it will always occupy the first entry if present.
-    DescriptorArray* descriptors = obj->map()->instance_descriptors();
-    if ((descriptors->number_of_descriptors() > 0) &&
-        (descriptors->GetKey(0) == isolate->heap()->hidden_symbol()) &&
-        descriptors->IsProperty(0)) {
-      ASSERT(descriptors->GetType(0) == FIELD);
-      return Handle<Object>(obj->FastPropertyAt(descriptors->GetFieldIndex(0)),
-                            isolate);
-    }
-  }
 
-  // Only attempt to find the hidden properties in the local object and not
-  // in the prototype chain.  Note that HasLocalProperty() can cause a GC in
-  // the general case in the presence of interceptors.
-  if (!obj->HasHiddenPropertiesObject()) {
-    // Hidden properties object not found. Allocate a new hidden properties
-    // object if requested. Otherwise return the undefined value.
-    if (create_if_needed) {
-      Handle<Object> hidden_obj =
-          isolate->factory()->NewJSObject(isolate->object_function());
-      CALL_HEAP_FUNCTION(isolate,
-                         obj->SetHiddenPropertiesObject(*hidden_obj), Object);
-    } else {
-      return isolate->factory()->undefined_value();
-    }
-  }
-  return Handle<Object>(obj->GetHiddenPropertiesObject(), isolate);
+Handle<Smi> GetIdentityHash(Handle<JSObject> obj) {
+  CALL_HEAP_FUNCTION(obj->GetIsolate(), obj->GetIdentityHash(), Smi);
 }