This will make mouse events other than click, mouseup, and mousedown become dispatched on disabled form controls instead of blocking them. It will also stop propagating click, mouseup, and mousedown events to the parents of disabled form controls when the event is targeted at a child of a disabled form control. A previous attempt at this was not shipped here: https://chromestatus.com/feature/5685077795143680
Disabled form controls should block events like click which can cause their form to be submitted, but not all mouse events: https://jakearchibald.com/2017/events-and-disabled-form-fields/