In Google Chrome, input[type=number] spin buttons are shown only on hover.
input[type=number]
You can target spin buttons using ::-webkit-inner/outer-spin-button and than just set opacity to 1 (spins are always there, but in default they have opacity: 0).
::-webkit-inner/outer-spin-button
opacity
opacity: 0
Code:
Fiddle: http://jsfiddle.net/dk8fj/