Minecraft 15w31c, Minecraft 15w32a, Minecraft 15w32b, Minecraft 15w32c
Enderdragon can destroy end_portal and end_gateway blocks
stand on portal
/setblock ~ ~5 ~ minecraft:end_gateway
/setblock ~ ~5 ~1 minecraft:end_portal
if enderdragon is already dead, summon a new one:
When he will fly through portal/getaway, they will be removed.