Background nodes appear wrong after round-tripping "leavesOnly"

[edbrannin]

Steps to reproduce:

1. Go to http://nivo.rocks/#/treemap
2. Click on the leavesOnly toggle.
3. Click on the leavesOnly toggle again.
4. (Bonus) Roll The Dice

Expected result:

• The treemap changes somehow, then changes back to how it looked before.
• Changing source data looks fine

Observed results:

1. Load page:
   
2. Leaves Only, On:
   
3. Leaves Only, Off:
   
4. Roll The Dice:
   

Also

Leaves Only says

Only render leaf nodes (no children).

Shouldn't that be (no parents)?

[plouc]

fixed