Hi,
Sorry if I butt in here, but I strongly oppose +/- buttons/icons in any cart details (menu item, module or checkout).
While it's ok in product listings and detail pages, cart rows are already sort of crowded near the quantity input with delete and reload icons. Adding more icons or so there creates, IMHO, more of a UX issue than benefit, especially on mobile devices.
Let's keep it clean instead? Especially since I've never heard of anyone being unable to figure out how to use the simple quantity input field.
Thank you.