new event type - DOM validation

[d0k1]

For making automated tests that works through UI jsflight should be able to store a valid reaction to user's clicks. For example, during a recording user clicks some buttons, and types some texts into fields, then user sees a reaction to that actions, and user have to store valid reaction. First thing that comes to mind, jsflight should explicitly store some part of DOM into recording as an event. Player could reproduce user's events and then player could make a try to validate browser's current DOM state against stored DOM state.