function setWidth() {
      var width = self.width || FALLBACK_WIDTH;
      var scrollbarWidth = self.scrollbarWidth;
      var scroller = childCtrl.calendarScroller;

      scrollMask.style.width = width + 'px';
      scroller.style.width = (width + scrollbarWidth) + 'px';
      scroller.style.paddingRight = scrollbarWidth + 'px';
    }
Hides the vertical scrollbar on the calendar scroller of a child controller by
setting the width on the calendar scroller and the `overflow: hidden` wrapper
around the scroller, and then setting a padding-right on the scroller equal
to the width of the browser's scrollbar.

This will cause a reflow.

@param {object} childCtrl The child controller whose scrollbar should be hidden.