When editing a post, make sure the corresponding partial is scrolled into view

[westonruter]

See https://core.trac.wordpress.org/ticket/39389

[westonruter]

This could be implemented in the JS Partial instances themselves. When refreshing any partial, it could call Element.scrollIntoView().

[westonruter]

This is something that should be in core generally, so I've also prepared a patch for a new trac ticket I opened: https://core.trac.wordpress.org/ticket/39389

@kienstra The patch could be applied to #220 for the deferred partial.