ObjectProxy.unknownProperty definesProperty

gistfile1.txt

var content = Em.Object.create({
  x: 1,
  y: 2,
  z: 0
});

var op = Em.ObjectProxy.createWithMixins({
  content: content,
  
  yBinding: 'x',

  _xDidChange: function() {
    this.set('z', this.get('x'));
  }.observes('x')

});

Em.run.sync();

alert(Em.inspect({content: Em.inspect(content.getProperties('x', 'y', 'z')), op: Em.inspect(op.getProperties('x', 'y', 'z'))}));

op.set('x', 3);
Em.run.sync();
             
// note the content.y not being propagated from the op
// caused by https://github.com/emberjs/ember.js/commit/8da6cb5d6a22687bb2409c43da582c95ab8e6744
//
alert(Em.inspect({content: Em.inspect(content.getProperties('x', 'y', 'z')), op: Em.inspect(op.getProperties('x', 'y', 'z'))}));