[WIP] Reordering in react-flip-move causes effects on MUVs

[albinotonnina]

Such as resetting scroll positions inside MUVs.
cause: https://github.com/joshwcomeau/react-flip-move/blob/master/src/FlipMove.js#L313-L326

[albinotonnina]

Needs to work on this.
Current Hacky fix is here:
https://github.com/albinotonnina/react-flip-move/blob/push_not_splice/src/FlipMove.js#L332-L344

[albinotonnina]

Also prepare a demo to reproduce the issue, which is:
MUVs with scrolling content get a scroll reset when navigating back to the root MUV, reason is the order of the children react-flip-move returns from the calculateNextSetOfChildren method.

Eg:

From: MUVs 2,3
To: MUVs 1,2

RFP needs to keep MUV 3 until the animation ends so it's more like this:

From: MUVs 2,3
MUVs 1,2,3
To: MUVs 1,2

Although react-flip-move order them like this:
From: MUVs 2,3
MUVs 1,3,2
To: MUVs 1,2

Hence the browser reset the scroll positions as an effect.