function changeResponder(nextResponderInst, blockHostResponder) {
  const oldResponderInst = responderInst;
  responderInst = nextResponderInst;
  if (ResponderEventPlugin.GlobalResponderHandler !== null) {
    ResponderEventPlugin.GlobalResponderHandler.onChange(
      oldResponderInst,
      nextResponderInst,
      blockHostResponder,
    );
  }
}
Count of current touches. A textInput should become responder iff the
selection changes while there is a touch on the screen.