Adding ElementsAccessor::Shift

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index a84d15015c4e3aa01ea5f7cb2cf780b42ad80249..6bcebd8a2e149361b2d8aac4221989ae46287db4 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -195,14 +195,6 @@ inline bool ClampedToInteger(Object* object, int* out) {
 }
 
 
-void MoveDoubleElements(FixedDoubleArray* dst, int dst_index,
-                        FixedDoubleArray* src, int src_index, int len) {
-  if (len == 0) return;
-  MemMove(dst->data_start() + dst_index, src->data_start() + src_index,
-          len * kDoubleSize);
-}
-
-
 inline bool GetSloppyArgumentsLength(Isolate* isolate, Handle<JSObject> object,
                                      int* out) {
   Map* arguments_map =
@@ -432,30 +424,7 @@ BUILTIN(ArrayShift) {
     return CallJsIntrinsic(isolate, isolate->array_shift(), args);
   }
 
-  // Get first element
-  Handle<Object> first;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, first,
-                                     Object::GetElement(isolate, array, 0));
-
-  if (heap->CanMoveObjectStart(*elms_obj)) {
-    array->set_elements(heap->LeftTrimFixedArray(*elms_obj, 1));
-  } else {
-    // Shift the elements.
-    if (elms_obj->IsFixedArray()) {
-      Handle<FixedArray> elms = Handle<FixedArray>::cast(elms_obj);
-      DisallowHeapAllocation no_gc;
-      heap->MoveElements(*elms, 0, 1, len - 1);
-      elms->set(len - 1, heap->the_hole_value());
-    } else {
-      Handle<FixedDoubleArray> elms = Handle<FixedDoubleArray>::cast(elms_obj);
-      MoveDoubleElements(*elms, 0, *elms, 1, len - 1);
-      elms->set_the_hole(len - 1);
-    }
-  }
-
-  // Set the length.
-  array->set_length(Smi::FromInt(len - 1));
-
+  Handle<Object> first = array->GetElementsAccessor()->Shift(array, elms_obj);
   return *first;
 }