Also call cancelAnimationFrame with the right context
Also call cancelAnimationFrame with the right context

Issue #418

kiejo/prosemirror,kiejo/prosemirror,kiejo/prosemirror,salzhrani/prosemirror,salzhrani/prosemirror,tzuhsiulin/prosemirror,tzuhsiulin/prosemirror,salzhrani/prosemirror,tzuhsiulin/prosemirror