Fix required blocks for 'draw a house' level s/1/level/90 [resolves #84263130]

Will support both solutions:

![image](https://cloud.githubusercontent.com/assets/206973/5369592/07ce55f8-7fcb-11e4-89d6-42310787d33c.png)

and

![image](https://cloud.githubusercontent.com/assets/206973/5369594/11eb2a5c-7fcb-11e4-8201-838f7204a2da.png)