Missing 'this' when dijit.form.Button's loadDropDown connects to dropDown's onLoad method

[Sam Foster]

var handler = dojo.connect(dropDown, "onLoad", function(){
  dojo.disconnect(handler);
  this.openDropDown();
});

'this' is referenced in the function, but not set in the connect() call.

[Sam Foster]

(In [21200]) Adding 'this' to the connect in Button's loadDropDown so the function is called with the widget as context. fixes #10650

[Adam Peller]

please don't forget the milestone