Revert of Remove GetAttributes from the mix to avoid another virtual dispatch.

src/elements.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ELEMENTS_H_
 #define V8_ELEMENTS_H_
 
 #include "src/elements-kind.h"
 #include "src/heap/heap.h"
 #include "src/isolate.h"
@@ skipping 42 matching lines @@
   // can optionally pass in the backing store to use for the check, which must
   // be compatible with the ElementsKind of the ElementsAccessor. If
   // backing_store is NULL, the holder->elements() is used as the backing store.
   virtual Handle<Object> Get(Handle<JSObject> holder, uint32_t key,
                              Handle<FixedArrayBase> backing_store) = 0;
 
   inline Handle<Object> Get(Handle<JSObject> holder, uint32_t key) {
     return Get(holder, key, handle(holder->elements()));
   }
 
+  // Returns an element's attributes, or ABSENT if there is no such
+  // element. This method doesn't iterate up the prototype chain.  The caller
+  // can optionally pass in the backing store to use for the check, which must
+  // be compatible with the ElementsKind of the ElementsAccessor. If
+  // backing_store is NULL, the holder->elements() is used as the backing store.
+  virtual PropertyAttributes GetAttributes(JSObject* holder, uint32_t key,
+                                           FixedArrayBase* backing_store) = 0;
+
+  inline PropertyAttributes GetAttributes(Handle<JSObject> holder,
+                                          uint32_t key) {
+    return GetAttributes(*holder, key, holder->elements());
+  }
+
   // Returns an element's accessors, or NULL if the element does not exist or
   // is plain. This method doesn't iterate up the prototype chain.  The caller
   // can optionally pass in the backing store to use for the check, which must
   // be compatible with the ElementsKind of the ElementsAccessor. If
   // backing_store is NULL, the holder->elements() is used as the backing store.
   virtual MaybeHandle<AccessorPair> GetAccessorPair(
       Handle<JSObject> holder, uint32_t key,
       Handle<FixedArrayBase> backing_store) = 0;
 
   inline MaybeHandle<AccessorPair> GetAccessorPair(Handle<JSObject> holder,
@@ skipping 93 matching lines @@
   // Element handlers distinguish between indexes and keys when they manipulate
   // elements.  Indexes refer to elements in terms of their location in the
   // underlying storage's backing store representation, and are between 0 and
   // GetCapacity.  Keys refer to elements in terms of the value that would be
   // specified in JavaScript to access the element. In most implementations,
   // keys are equivalent to indexes, and GetKeyForIndex returns the same value
   // it is passed. In the NumberDictionary ElementsAccessor, GetKeyForIndex maps
   // the index to a key using the KeyAt method on the NumberDictionary.
   virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store,
                                   uint32_t index) = 0;
-  virtual uint32_t GetIndexForKey(JSObject* holder,
-                                  FixedArrayBase* backing_store,
+  virtual uint32_t GetIndexForKey(FixedArrayBase* backing_store,
                                   uint32_t key) = 0;
   virtual PropertyDetails GetDetails(FixedArrayBase* backing_store,
                                      uint32_t index) = 0;
   virtual bool HasIndex(FixedArrayBase* backing_store, uint32_t key) = 0;
 
   virtual Handle<Object> Set(Handle<JSObject> holder, uint32_t key,
                              Handle<FixedArrayBase> backing_store,
                              Handle<Object> value) = 0;
 
  private:
   static ElementsAccessor** elements_accessors_;
   const char* name_;
 
   DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
 };
 
 void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t key,
                      bool allow_appending = false);
 
 MUST_USE_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
     Handle<JSArray> array,
     Arguments* args);
 
 } }  // namespace v8::internal
 
 #endif  // V8_ELEMENTS_H_