Implement Array.observe and emit splice change records for ArrayPush

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 1050 matching lines @@
 
 
 // Tests for array methods, first on arrays and then on plain objects
 //
 // === ARRAYS ===
 //
 // Push
 reset();
 var array = [1, 2];
 Object.observe(array, observer.callback);
+Array.observe(array, observer2.callback);
 array.push(3, 4);
+array.push(5);
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
   { object: array, name: '2', type: 'new' },
   { object: array, name: 'length', type: 'updated', oldValue: 2 },
   { object: array, name: '3', type: 'new' },
   { object: array, name: 'length', type: 'updated', oldValue: 3 },
+  { object: array, name: '4', type: 'new' },
+  { object: array, name: 'length', type: 'updated', oldValue: 4 },
+]);
+Object.deliverChangeRecords(observer2.callback);
+observer2.assertCallbackRecords([
+  { object: array, type: 'splice', index: 2, removed: [], addedCount: 2 },
+  { object: array, type: 'splice', index: 4, removed: [], addedCount: 1 }
 ]);
 
 // Pop
 reset();
 var array = [1, 2];
 Object.observe(array, observer.callback);
 array.pop();
 array.pop();
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
@@ skipping 290 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);