Call requestAnimationFrame with window as self/this
Call requestAnimationFrame with window as self/this

Closes #418

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