code: function _Overlay_baseAnimateIn() {
                      this._element.style.opacity = 0;
                      this._element.style.visibility = "visible";
                      // touch opacity so that IE fades from the 0 we just set to 1
                      _ElementUtilities._getComputedStyle(this._element, null).opacity;
                      return Animations.fadeIn(this._element);
                  }
docs: Default animations