Object.observe: Move notification of JSArray length changes to JSArray::SetElementsLength

src/accessors.cc

Index: src/accessors.cc
diff --git a/src/accessors.cc b/src/accessors.cc
index c2f245cd9a516411770aba93da70afe159541830..855ddb22b6731e7c59caadbcf90157678968ae40 100644
--- a/src/accessors.cc
+++ b/src/accessors.cc
@@ -95,47 +95,6 @@ Object* Accessors::FlattenNumber(Object* value) {
 }
 
 
-static MaybeObject* ArraySetLengthObserved(Isolate* isolate,
-                                           Handle<JSArray> array,
-                                           Handle<Object> new_length_handle) {
-  List<Handle<String> > indices;
-  List<Handle<Object> > old_values;
-  Handle<Object> old_length_handle(array->length(), isolate);
-  uint32_t old_length = 0;
-  CHECK(old_length_handle->ToArrayIndex(&old_length));
-  uint32_t new_length = 0;
-  CHECK(new_length_handle->ToArrayIndex(&new_length));
-  // TODO(adamk): This loop can be very slow for arrays in dictionary mode.
-  // Find another way to iterate over arrays with dictionary elements.
-  for (uint32_t i = old_length - 1; i + 1 > new_length; --i) {
-    PropertyAttributes attributes = array->GetLocalElementAttribute(i);
-    if (attributes == ABSENT) continue;
-    // A non-configurable property will cause the truncation operation to
-    // stop at this index.
-    if (attributes == DONT_DELETE) break;
-    // TODO(adamk): Don't fetch the old value if it's an accessor.
-    old_values.Add(Object::GetElement(array, i));
-    indices.Add(isolate->factory()->Uint32ToString(i));
-  }
-
-  MaybeObject* result = array->SetElementsLength(*new_length_handle);
-  Handle<Object> hresult;
-  if (!result->ToHandle(&hresult)) return result;
-
-  CHECK(array->length()->ToArrayIndex(&new_length));
-  if (old_length != new_length) {
-    for (int i = 0; i < indices.length(); ++i) {
-      JSObject::EnqueueChangeRecord(
-          array, "deleted", indices[i], old_values[i]);
-    }
-    JSObject::EnqueueChangeRecord(
-        array, "updated", isolate->factory()->length_symbol(),
-        old_length_handle);
-  }
-  return *hresult;
-}
-
-
 MaybeObject* Accessors::ArraySetLength(JSObject* object, Object* value, void*) {
   Isolate* isolate = object->GetIsolate();
 
@@ -163,11 +122,7 @@ MaybeObject* Accessors::ArraySetLength(JSObject* object, Object* value, void*) {
   if (has_exception) return Failure::Exception();
 
   if (uint32_v->Number() == number_v->Number()) {
-    if (FLAG_harmony_observation && array_handle->map()->is_observed()) {
-      return ArraySetLengthObserved(isolate, array_handle, uint32_v);
-    } else {
-      return array_handle->SetElementsLength(*uint32_v);
-    }
+    return array_handle->SetElementsLength(*uint32_v);
   }
   return isolate->Throw(
       *isolate->factory()->NewRangeError("invalid_array_length",