In other browsers, if you carry on scrolling an element past the end then its parent element will begin to scroll, if possible.

In Servo, the parent element does not begin to scroll once the inner element has been scrolled all the way down.

Expected behaviour as shown in FF (identical in Chrome):

However, in Servo the parent element does not begin to scroll once the user has scrolled to the very end of the inner element.

Page used for testing can be found online here.