Flying, haste
You may cast sorcery spells as though they had flash. (You may cast them any time you could cast an instant.)
Hypersonic Dragon’s last ability applies to sorcery cards in any zone, provided something is allowing you to cast them. For example, you could cast a sorcery with flashback as though it had flash.
Hypersonic Dragon’s last ability has no effect on abilities that you can activate “any time you could cast a sorcery.”