Manipulating range sliders with arrow keys does not respect `allowCross` prop

[justinpchang]

Example:

<Slider
  allowCross={false}
  range
  vertical
  reverse
  value={...}
  min={1}
  max={10}
  dots
  handleRender={...}
  onChange={...}
/>

If you click on a slider handle and use the arrow keys to go up and down, you can cross the other slider even though allowCross is set to false.