
      // Hide the overlay and remove the backdrop.
      this.style.display = 'none';
      // Reset z-index only at the end of the animation.
      this.style.zIndex = '';

      this._applyFocus();

      this.notifyResize();
      this.__isAnimating = false;
      this.fire('iron-overlay-closed', this.closingReason);
    },

    _preparePositioning: function() {
      this.style.transition = this.style.webkitTransition = 'none';
      this.style.transform = this.style.webkitTransform = 'none';
      thi