code: function changeProperties(callback, binding) {
      beginPropertyChanges();
      try {
        callback.call(binding);
      } finally {
        endPropertyChanges.call(binding);
      }
    }
docs: Make a series of property changes together in an
  exception-safe way.
  
  ```javascript
  Ember.changeProperties(function() {
  obj1.set('foo', mayBlowUpWhenSet);
  obj2.set('bar', baz);
  });
  ```
  
  @method changeProperties
  @param {Function} callback
  @param [binding]
  @private