Refactor how elements are redefined by the runtime.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index efb7aeeccdf6288740a073f39b82c1ee4d3aaaac..0cafaf591e0c59690414feae72c8642f3b20b0d5 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -4232,7 +4232,6 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DefineOrRedefineDataProperty) {
   // DONT_DELETE: false, DONT_ENUM: false, READ_ONLY: false.
   if (is_element && (attr != NONE ||
       js_object->HasLocalElement(index) == JSObject::DICTIONARY_ELEMENT)) {
-    // Normalize the elements to enable attributes on the property.
     if (js_object->IsJSGlobalProxy()) {
       // We do not need to do access checks here since these has already
       // been performed by the call to GetOwnProperty.
@@ -4253,19 +4252,10 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DefineOrRedefineDataProperty) {
       return isolate->Throw(*error);
     }
 
-    Handle<NumberDictionary> dictionary = NormalizeElements(js_object);
-    // Make sure that we never go back to fast case.
-    dictionary->set_requires_slow_elements();
-    PropertyDetails details = PropertyDetails(attr, NORMAL);
-    Handle<NumberDictionary> extended_dictionary =
-        NumberDictionarySet(dictionary, index, obj_value, details);
-    if (*extended_dictionary != *dictionary) {
-      if (js_object->GetElementsKind() == NON_STRICT_ARGUMENTS_ELEMENTS) {
-        FixedArray::cast(js_object->elements())->set(1, *extended_dictionary);
-      } else {
-        js_object->set_elements(*extended_dictionary);
-      }
-    }
+    js_object->GetElementsAccessor()->Set(*js_object,
+                                          index,
+                                          *obj_value,
+                                          attr);
     return *obj_value;
   }