Hot Streak and some other proc buffs not being used on cast

[silentwinter]

As the title states, Hot Streak and some other proc buffs that let you instant-cast the next (whatever) ability are not being used on cast, but instead are being used on impact.

OpenWoW/WoWHead Link

https://www.youtube.com/watch?v=kt_08IyzFS4
Video from Blizzard. You see him DPS-ing and you can see Hot Streak buff being consumed right on the cast instead of on impact.

Expected Behavior

Hot Streak (And other buffs) should be consumed right on the cast.

Current Behavior

The Buffs are being consumed on impact.

Possible Solution

Change the condition to "on the cast" instead of "on the impact"

Steps to Reproduce

1. Get Hot Streak
2. Cast Pyroblast
3. See the buff not being consumed on cast.
4. See the buff being consumed on impact.

Context (Environment)

More enjoy-able playing experience.

Screenshots

https://www.youtube.com/watch?v=kt_08IyzFS4