[UI][Air Client] Small shop bug for champions on sale.

Ok this is a really small bug but it's there.

Repro steps:

• Launch the client
• Go to the champion store
• Take a champion on sale, for which you dont have enough IP to buy it, but you got more IP than half of the price, ex.: Tahm is today on sale, he's for 6300IP (I've got 6273IP), however the "IP text color" is white as if Tahm would cost less than 6300IP, probably the IP value that is checked agains your current IP is also 50% of the total champion price, thus it appears to me as if I could buy Tahm while not having enough IP.