constructor(configuration = {}) {
    const logLevel = Configuration.option('logLevel');

    this.logger = configuration.logger || new Logger(logLevel);

    this.focusOnlyEventStrategy =
      new FocusOnlyKeyEventStrategy({ configuration, logLevel }, this);

    this.globalEventStrategy =
      new GlobalKeyEventStrategy({ configuration, logLevel }, this);

    this.mountedComponentsCount = 0;

    this._blurHandler = this._clearKeyHistory.bind(this);
  }
Creates a new KeyEventManager instance. It is expected that only a single instance
will be used with a render tree.