Does Mask of Foresight target Ireila to get +1?

No, Mask of Foresight does not target Irelia, Fervent.

According to the RiftJudge FAQ (ID 9418) and Core Rules regarding targeting (Rule 355.10):

• Mask of Foresight does not target: The ability reads, "When a friendly unit attacks or defends alone, give it +1 might this turn." It does not use the word "target," and it does not meet the criteria for targeting defined in Rule 355.10. It automatically applies to the specific unit that triggered it.
• No trigger for Irelia: Because Mask of Foresight does not "choose" or "ready" the unit (it is an automatic effect), it does not satisfy the trigger condition of Irelia, Fervent ("When you choose or ready me, give me +1 might this turn").

As confirmed by RiftJudge FAQ (ID 5224), Irela Fervent's ability specifically requires "you" (the player) to perform the action of choosing or readying her. Effects that happen automatically, such as Mask of Foresight's bonus, do not count as player choices and therefore do not trigger Irelia's ability.