replaceState(oldState, newState) {
    return new ConditionalState(
        State.replaceStateId(this.id, oldState, newState),
        State.replaceStateId(this.ifState, oldState, newState),
        State.replaceStateId(this.elseState, oldState, newState),
        this.condition);
  }
Represents the dispatch portion of an if/else block.
ConditionalStates are immutable.

@param {number} oldState
@param {number} newState
@return {ConditionalState}