message: Fix handling of the platform onKeyDown
  Only call it if the event hasn't been handled yet.
diff: @@ -485,9 +485,10 @@ class LoggedInView extends React.Component<IProps, IState> {
  unread: true,
  });
  break;
  - }
  + default:
  // if we do not have a handler for it, pass it to the platform which might
  handled = PlatformPeg.get().onKeyDown(ev);
  + }
  if (handled) {
  ev.stopPropagation();
  ev.preventDefault();
  