SC.Object.reopen does not honor concatenatedProperties

[mauritslamers]

The SproutCore OO system has a system called concatenated properties, which allows certain properties to be appended to when extending or creating. One such example is the displayProperties on SC.View, and concatenatedProperties itself.

However, when SC.Object.reopen is used, any properties that are defined in the concatenatedProperties property or in the concatenatedProperties array itself are removed from the extensions hash.
This leads to unexpected results when using reopen(), such as that certain properties will suddenly disappear or not being considered when using reopen multiple times.

The example below uses the attributeBindings property, which is defined as part of the concatenatedProperties array in SC.View.

SC.View.reopen({

  attributeBindings: ['test'],

  test: 'somevalue',
});

SC.View.reopen({
  attributeBindings: ['test2'],

  test2: 'someothervalue',

});

// when inspecting the SC.View.prototype:
>> SC.View.prototype
{
...
attributeBindings: ['test'],
...
}
// expected result
>> SC.View.prototype
{
...
attributeBindings: ['test', 'test2'],
...
}