Fix FocusMana event registration on Classic builds

Thanks to Lethay's comments on WowAce.

changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+v1.13.9:
+
+- Fixed FocusMana modules attempting to register invalid events in Classic builds.
+
 v1.13.8.1:
 
 - Updated TOC for BC-Classic and Classic.

modules/FocusMana.lua

@@ -39,9 +39,9 @@ end
 function FocusMana.prototype:Enable(core)
 	FocusMana.super.prototype.Enable(self, core)
 
-	if IceHUD.WowVer >= 40000 then
+	if not IceHUD.PerPowerEventsExist then
 		self:RegisterEvent(IceHUD.UnitPowerEvent, "UpdateEvent")
-		if IceHUD.WowVer < 80000 then
+		if IceHUD.EventExistsUnitMaxPower then
 			self:RegisterEvent("UNIT_MAXPOWER", "UpdateEvent")
 		end
 	else

this_version.md

@@ -1,6 +1,5 @@
 # Changelog
 
-v1.13.8.1:
+vNext:
 
-- Fixed Paladin GCD not functioning in BC-Classic.
-- Updated TOC for BC-Classic and Classic.
+- Fixed FocusMana modules attempting to register invalid events in Classic builds.