fire mouse up at the ownerDocument instead of document

[danielschranz]

Similar to the change in this commit: 779bcef

Should the mouseup event also get fired on target.ownerDocument instead of document?
(here: https://github.com/jquery/jquery-simulate/blob/master/jquery.simulate.js#L325)

This change fixes an issue with drag and drop within an iframe for me. (Not sure if it has other implications, though)