It's going to take some extra work to make rubber-banding work for overflow:scroll in WebKit 1. Right now there is a problem where the rubber-band timer fires but we often get into a state where the conditions that we expect to be met in order to finish the rubber-band have not been met, so the timer just keeps firing, and we never finish the rubber-band. This is a follow-up bug for https://bugs.webkit.org/show_bug.cgi?id=91655
No idea if this is still relevant.