Cast slow mechanic values way off

[henhouse]

I'm noticing the slow-cast speed values are way off. For example, Holy Light -- a 2.5-second cast, with a 60% increase to that cast (1.5 seconds) should be 4 seconds. Instead, the cast speed is 6.25 seconds. A 50% increase to cast speed (from, say, Mind-numbing Poison) is 5 seconds -- 100% increase in cast speed, double what it should be.

[ratkosrb]

Confirmed and fixed here -> 853e77c