Bug 976673 part.1 Add tests r=enndeakin
Bug 976673 part.2 Allow to steal focus by JS at handling mouseup event r=enndeakin
Bug 976673 part.3 Don't synthesize mouse events while another mouse event is being synthesized r=smaug
Bug 976673 part.4 Allow nested mouse button event handling for modal dialog r=smaug+enndeakin