closure_compiler: Fix type annoation for |Map.prototype.keys|, |Map.prototype.values|, |Set.prototype.keys| and |Set.prototype.values|.
[evita] dom/text: Use |Symbol| for |Document.prototype.obsolete| property instead of number.
[evita] dom/events: Introduce |domapi::Event::event_id| for detecting pending input events.
[evita] ui: Revise native window destroying sequence.
[evita] dom: Make ES6'ish.