code: function getFixedScrollOffset(offset, length) {
          if (offset && length + offset <= limit) {
            return Math.min(limit - length, 0);
          }
          return Math.min(offset, 0);
        }
docs: Given an offset and length, get the corrected offset.
  
  @param {Number} offset
  The current offset value.
  
  @param {Number} length
  The length of available data to offset.
  
  @returns {Number}
  The corrected scroll offset is returned.