When notifying observers of a truncated array, don't call getters on deleted element indices

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 566 matching lines @@
 arr.length = 0;
 arr.length = 10;
 arr2.length = 0;
 arr2.length = 1; // no change expected
 arr3.length = 0;
 Object.defineProperty(arr3, 'length', {value: 5});
 Object.defineProperty(arr3, 'length', {value: 10, writable: false});
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
   { object: arr, name: '3', type: 'deleted', oldValue: 'd' },
-  // TODO(adamk): oldValue should not be present below
-  { object: arr, name: '2', type: 'deleted', oldValue: undefined },
+  { object: arr, name: '2', type: 'deleted' },
   { object: arr, name: 'length', type: 'updated', oldValue: 4 },
   { object: arr, name: '1', type: 'deleted', oldValue: 'b' },
   { object: arr, name: 'length', type: 'updated', oldValue: 2 },
   { object: arr, name: 'length', type: 'updated', oldValue: 1 },
   { object: arr2, name: '1', type: 'deleted', oldValue: 'beta' },
   { object: arr2, name: 'length', type: 'updated', oldValue: 2 },
   { object: arr3, name: '2', type: 'deleted', oldValue: 'goodbye' },
   { object: arr3, name: '0', type: 'deleted', oldValue: 'hello' },
   { object: arr3, name: 'length', type: 'updated', oldValue: 6 },
   { object: arr3, name: 'length', type: 'updated', oldValue: 0 },
@@ skipping 205 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},
 ]);