Elixir Master

Elixir Master does not work for Legion crafting either

I just completed gathering all of the ingredients necessary for this quest just after patch 5.0.4 was released. Guess what, everything changed, now it's a level 90 quest.

new elixirs required: X 2 each
Flast of Winter's Bite
Flast of Earth
Flast of Warm Sun
Flast of Springs Blossoms

requiring:
Fools Cap (8)
Golden Lotus (8)
Rain Poppy (8)
Silkweed (8)
Snow Lilly (8)

Not gonna happen.

Since I was waiting to level for the Darkmoon Faire, I can confirm that this quest (including all of the Mastery quests for Alchemy) can be found from [npc=5499] on alliance-side. However, she did not offer the quests until I hit 475 in alchemy.

I also couldn't find the old quests.

In short, you now must wait until 475 in alchemy to pick a mastery (unless you already picked one before the patch).

Edit to add: The quest gives you nothing more than the mastery in exchange for all the elixirs (went elixir mastery). I was 81 at the time of completion (bought the elixirs for the quest off the AH).