Applying splices containing add-before-remove changes (i.e. move) breaks Collection

[kevinpschaaf]

Minimum repro:
http://jsbin.com/jocowevohi/edit?html,output (add before remove: bad)
vs.
http://jsbin.com/lenapi/edit?html,output (remove before add: good)

More complicated sort:
http://jsbin.com/sofejo/edit?html,output

[kevinpschaaf]

Fixed sort repro using fix branch: http://jsbin.com/tajeda/edit?html,output