getDictionaryKey = function (inst) {
  // Prevents V8 performance issue:
  // https://github.com/facebook/react/pull/7232
  return '.' + inst._rootNodeID;
}
Deletes a listener from the registration bank.

@param {object} inst The instance, which is the source of events.
@param {string} registrationName Name of listener (e.g. `onClick`).