Object.observe/unobserve now return object

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 80 matching lines @@
     recordCreated = true;
     return "bar";
   },
   enumerable: true
 })
 
 // Object.observe
 assertThrows(function() { Object.observe("non-object", observer.callback); }, TypeError);
 assertThrows(function() { Object.observe(obj, nonFunction); }, TypeError);
 assertThrows(function() { Object.observe(obj, frozenFunction); }, TypeError);
+assertEquals(obj, Object.observe(obj, observer.callback));
 
 // Object.unobserve
 assertThrows(function() { Object.unobserve(4, observer.callback); }, TypeError);
 assertThrows(function() { Object.unobserve(obj, nonFunction); }, TypeError);
+assertEquals(obj, Object.unobserve(obj, observer.callback));
 
 // Object.getNotifier
 var notifier = Object.getNotifier(obj);
 assertSame(notifier, Object.getNotifier(obj));
 assertEquals(null, Object.getNotifier(Object.freeze({})));
 assertFalse(notifier.hasOwnProperty('notify'));
 assertEquals([], Object.keys(notifier));
 var notifyDesc = Object.getOwnPropertyDescriptor(notifier.__proto__, 'notify');
 assertTrue(notifyDesc.configurable);
 assertTrue(notifyDesc.writable);
@@ skipping 499 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},
 ]);