Use GetProperty for getting elements.

src/elements.h

Index: src/elements.h
diff --git a/src/elements.h b/src/elements.h
index f4d15fc828b751ab8f4c488e85f1586d4c001fa6..1065b1f73df63aa492a766cefa3e309dbbf2bb64 100644
--- a/src/elements.h
+++ b/src/elements.h
@@ -48,17 +48,11 @@ class ElementsAccessor {
   // 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.
-  MUST_USE_RESULT virtual MaybeHandle<Object> Get(
-      Handle<Object> receiver,
-      Handle<JSObject> holder,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) = 0;
+  virtual Handle<Object> Get(Handle<JSObject> holder, uint32_t key,
+                             Handle<FixedArrayBase> backing_store) = 0;
 
-  MUST_USE_RESULT inline MaybeHandle<Object> Get(
-      Handle<Object> receiver,
-      Handle<JSObject> holder,
-      uint32_t key) {
-    return Get(receiver, holder, key, handle(holder->elements()));
+  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
@@ -66,15 +60,12 @@ class ElementsAccessor {
   // 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.
-  MUST_USE_RESULT virtual PropertyAttributes GetAttributes(
-      Handle<JSObject> holder,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) = 0;
+  virtual PropertyAttributes GetAttributes(JSObject* holder, uint32_t key,
+                                           FixedArrayBase* backing_store) = 0;
 
-  MUST_USE_RESULT inline PropertyAttributes GetAttributes(
-      Handle<JSObject> holder,
-      uint32_t key) {
-    return GetAttributes(holder, key, handle(holder->elements()));
+  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
@@ -82,14 +73,12 @@ class ElementsAccessor {
   // 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.
-  MUST_USE_RESULT virtual MaybeHandle<AccessorPair> GetAccessorPair(
-      Handle<JSObject> holder,
-      uint32_t key,
+  virtual MaybeHandle<AccessorPair> GetAccessorPair(
+      Handle<JSObject> holder, uint32_t key,
       Handle<FixedArrayBase> backing_store) = 0;
 
-  MUST_USE_RESULT inline MaybeHandle<AccessorPair> GetAccessorPair(
-      Handle<JSObject> holder,
-      uint32_t key) {
+  inline MaybeHandle<AccessorPair> GetAccessorPair(Handle<JSObject> holder,
+                                                   uint32_t key) {
     return GetAccessorPair(holder, key, handle(holder->elements()));
   }
 
@@ -158,7 +147,7 @@ class ElementsAccessor {
       *from_holder, 0, from_kind, to, 0, kCopyToEndAndInitializeToHole);
   }
 
-  MUST_USE_RESULT virtual MaybeHandle<FixedArray> AddElementsToFixedArray(
+  virtual Handle<FixedArray> AddElementsToFixedArray(
       Handle<JSObject> receiver, Handle<FixedArray> to,
       FixedArray::KeyFilter filter) = 0;
 
@@ -196,6 +185,7 @@ class ElementsAccessor {
                                   uint32_t key) = 0;
   virtual PropertyDetails GetDetails(FixedArrayBase* backing_store,
                                      uint32_t index) = 0;
+  virtual bool HasIndex(FixedArrayBase* backing_store, uint32_t key) = 0;
 
  private:
   static ElementsAccessor** elements_accessors_;