[Object.observe] Don't force normalization of elements for observed objects

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 596 matching lines @@
   { object: thingy, type: Thingy.MULTIPLY, multiplied: 2 },
   { object: thingy, type: 'update', name: 'a', oldValue: 10 },
   {
     object: thingy,
     type: Thingy.INCREMENT_AND_MULTIPLY,
     incremented: 2,
     multiplied: 2
   }
 ]);
 
+// ArrayPush cached stub
+reset();
+
+function pushMultiple(arr) {
+  arr.push('a');
+  arr.push('b');
+  arr.push('c');
+}
+
+for (var i = 0; i < 5; i++) {
+  var arr = [];
+  pushMultiple(arr);
+}
+
+for (var i = 0; i < 5; i++) {
+  reset();
+  var arr = [];
+  Object.observe(arr, observer.callback);
+  pushMultiple(arr);
+  Object.unobserve(arr, observer.callback);
+  Object.deliverChangeRecords(observer.callback);
+  observer.assertCallbackRecords([
+    { object: arr, type: 'add', name: '0' },
+    { object: arr, type: 'update', name: 'length', oldValue: 0 },
+    { object: arr, type: 'add', name: '1' },
+    { object: arr, type: 'update', name: 'length', oldValue: 1 },
+    { object: arr, type: 'add', name: '2' },
+    { object: arr, type: 'update', name: 'length', oldValue: 2 },
+  ]);
+}
+
+
+// ArrayPop cached stub
+reset();
+
+function popMultiple(arr) {
+  arr.pop();
+  arr.pop();
+  arr.pop();
+}
+
+for (var i = 0; i < 5; i++) {
+  var arr = ['a', 'b', 'c'];
+  popMultiple(arr);
+}
+
+for (var i = 0; i < 5; i++) {
+  reset();
+  var arr = ['a', 'b', 'c'];
+  Object.observe(arr, observer.callback);
+  popMultiple(arr);
+  Object.unobserve(arr, observer.callback);
+  Object.deliverChangeRecords(observer.callback);
+  observer.assertCallbackRecords([
+    { object: arr, type: 'delete', name: '2', oldValue: 'c' },
+    { object: arr, type: 'update', name: 'length', oldValue: 3 },
+    { object: arr, type: 'delete', name: '1', oldValue: 'b' },
+    { object: arr, type: 'update', name: 'length', oldValue: 2 },
+    { object: arr, type: 'delete', name: '0', oldValue: 'a' },
+    { object: arr, type: 'update', name: 'length', oldValue: 1 },
+  ]);
+}
+
 
 reset();
 function RecursiveThingy() {}
 
 RecursiveThingy.MULTIPLY_FIRST_N = 'multiplyFirstN';
 
 RecursiveThingy.prototype = {
   __proto__: Array.prototype,
 
   multiplyFirstN: function(amount, n) {
@@ skipping 1089 matching lines @@
     for (var n1 = 0; n1 < 3; ++n1)
       for (var n2 = 0; n2 < 3; ++n2)
         for (var i in mutation)
           TestFastElementsLength(mutation[i], b1 != 0, b2 != 0, 20*n1, 20*n2);
 
 for (var b1 = 0; b1 < 2; ++b1)
   for (var b2 = 0; b2 < 2; ++b2)
     for (var n = 0; n < 3; ++n)
       for (var i in mutationByIncr)
         TestFastElementsLength(mutationByIncr[i], b1 != 0, b2 != 0, 7*n, 7*n+1);