[key-accumulator] Starting to reimplement the key-accumulator

src/elements.h

Index: src/elements.h
diff --git a/src/elements.h b/src/elements.h
index 07f24c1f8c6b920a0af93698a40e95b80e2211b3..4657c83c69b7c1228ca729ca1ed8b9e5eccc8b35 100644
--- a/src/elements.h
+++ b/src/elements.h
@@ -99,6 +99,19 @@ class ElementsAccessor {
                           filter, offset);
   }
 
+  //
+  virtual Handle<FixedArray> PrependElementIndices(
+      Handle<JSObject> object, Handle<FixedArrayBase> backing_store,
+      Handle<FixedArray> keys, GetKeysConversion convert,
+      PropertyFilter filter = ALL_PROPERTIES) = 0;
+
+  inline Handle<FixedArray> PrependElementIndices(
+      Handle<JSObject> object, Handle<FixedArray> keys,
+      GetKeysConversion convert, PropertyFilter filter = ALL_PROPERTIES) {
+    return PrependElementIndices(object, handle(object->elements()), keys,
+                                 convert, filter);
+  }
+
   virtual void AddElementsToKeyAccumulator(Handle<JSObject> receiver,
                                            KeyAccumulator* accumulator,
                                            AddKeyConversion convert) = 0;