Object.observe: Use [[DefineOwnProperty]] to create properties of changeRecord

test/mjsunit/harmony/object-observe.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 110 matching lines @@
 assertThrows(function() { notify.call('hello', { type: 'a' }); }, TypeError);
 assertThrows(function() { notify.call(false, { type: 'a' }); }, TypeError);
 assertThrows(function() { notify.call({}, { type: 'a' }); }, TypeError);
 assertFalse(recordCreated);
 notifier.notify(changeRecordWithAccessor);
 assertFalse(recordCreated);  // not observed yet
 
 // Object.deliverChangeRecords
 assertThrows(function() { Object.deliverChangeRecords(nonFunction); }, TypeError);
 
+Object.observe(obj, observer.callback);
+
+// notify uses to [[CreateOwnProperty]] to create changeRecord;
+reset();
+var protoExpandoAccessed = false;
+Object.defineProperty(Object.prototype, 'protoExpando',
+  {
+    configurable: true,
+    set: function() { protoExpandoAccessed = true; }
+  }
+);
+notifier.notify({ type: 'foo', protoExpando: 'val'});
+assertFalse(protoExpandoAccessed);
+delete Object.prototype.protoExpando;
+Object.deliverChangeRecords(observer.callback);
+
 // Multiple records are delivered.
-Object.observe(obj, observer.callback);
+reset();
 notifier.notify({
   type: 'updated',
   name: 'foo',
   expando: 1
 });
 
 notifier.notify({
   object: notifier,  // object property is ignored
   type: 'deleted',
   name: 'bar',
@@ skipping 454 matching lines @@
 Object.observe(dummy, observer.callback);
 Object.unobserve(dummy, observer.callback);
 var array = [0];
 Object.observe(array, observer.callback);
 array.splice(0, 1);
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
   { object: array, name: '0', type: 'deleted', oldValue: 0 },
   { object: array, name: 'length', type: 'updated', oldValue: 1},
 ]);