docs/bundle.js
function trapBubbledEvent(topLevelType, handlerBaseName, element) {
  if (!element) {
    return null;
  }
  return EventListener.listen(element, handlerBaseName, dispatchEvent.bind(null, topLevelType));
}
function trapBubbledEvent(topLevelType, handlerBaseName, element) {
  if (!element) {
    return null;
  }
  return EventListener.listen(element, handlerBaseName, dispatchEvent.bind(null, topLevelType));
}
Traps top-level events by using event bubbling.

@param {string} topLevelType Record from `BrowserEventConstants`.
@param {string} handlerBaseName Event name (e.g. "click").
@param {object} element Element on which to attach listener.
@return {?object} An object with a remove function which will forcefully
remove the listener.
@internal