Stop sending Object.observe notifications for API accessor properties

src/v8natives.js

 // 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.
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Object = global.Object;
 // var $Boolean = global.Boolean;
 // var $Number = global.Number;
 // var $Function = global.Function;
@@ skipping 869 matching lines @@
         var deletedDesc = GetOwnPropertyJS(obj, index);
         if (deletedDesc && deletedDesc.hasValue())
           removed[length - new_length] = deletedDesc.getValue();
       }
       if (!Delete(obj, index, false)) {
         new_length = length + 1;
         threw = true;
         break;
       }
     }
-    // Make sure the below call to DefineObjectProperty() doesn't overwrite
-    // any magic "length" property by removing the value.
-    // TODO(mstarzinger): This hack should be removed once we have addressed the
-    // respective TODO in Runtime_DefineDataPropertyUnchecked.

[adamk, 2014/12/11 20:26:07]

This TODO was taken care of by r21558, so at least we can remove this weird "set
the length twice" hack.

-    // For the time being, we need a hack to prevent Object.observe from
-    // generating two change records.
-    obj.length = new_length;
-    desc.value_ = UNDEFINED;
-    desc.hasValue_ = false;
     threw = !DefineObjectProperty(obj, "length", desc, should_throw) || threw;
     if (emit_splice) {
       EndPerformSplice(obj);
       EnqueueSpliceRecord(obj,
           new_length < old_length ? new_length : old_length,
           removed,
           new_length > old_length ? new_length - old_length : 0);
     }
     if (threw) {
       if (should_throw) {
@@ skipping 988 matching lines @@
   }
   if (!IS_SPEC_FUNCTION(method)) {
     throw MakeTypeError('not_iterable', [obj]);
   }
   var iterator = %_CallFunction(obj, method);
   if (!IS_SPEC_OBJECT(iterator)) {
     throw MakeTypeError('not_an_iterator', [iterator]);
   }
   return iterator;
 }