function StepsRunner() {
  /**
   * Function to notify the end of the current closure.
   * @type {?function}
   * @private
   */
  this.next_ = null;
}
/**
 * Executes a sequence of test steps.
 * @constructor
 */
Executes a sequence of test steps.
@constructor
Executes a sequence of test steps . @constructor
function StepsRunner() {
  this.next_ = null;
}
function StepsRunner ( ) { this . next_ = null ; }
Executes a sequence of test steps.
Executes a sequence of test steps .
/**
   * Function to notify the end of the current closure.
   * @type {?function}
   * @private
   */