I want to make sure I understand what Corki's passive is

It says "Corki's basic attacks deal 10% bonus damage," but lately Riot's been implementing unique drawbacks into champions to balance them out, so I want to make sure what it means.

Does it mean: Corki's basic attacks deal 100% of his normal bonus damage plus an additional 10% of his bonus damage. Or Corki's basic attacks only deal 10% of bonus damage instead of 100% of bonus damage because Riot is afraid his burst would bee too strong otherwise, aka if his bonus attack damage is +100ad, his basic attacks ONLY deal +10ad instead.