GetItemButtonIconTexture Calls a Missing Function

[StormFX]

With 11.1, the ItemButtonMixin code was moved to Interface\AddOns\Blizzard_ItemButton\Shared\ItemButtonTemplate.lua. In the process of moving the code over, a local function, GetItemButtonIconTexture, was not moved over so the button method by the same name that calls that local function throws an error when that method is called. Relevant code:

Interface\AddOns\Blizzard_ItemButton\Shared\ItemButtonTemplate.lua 255-257

function ItemButtonMixin:GetItemButtonIconTexture()
	return GetItemButtonIconTexture(self);
end

Interface\AddOns\Blizzard_ItemButton\Mainline\ItemButtonTemplate.lua 10-12

local function GetItemButtonIconTexture(button)
	return button.Icon or button.icon or _G[button:GetName().."IconTexture"];
end

[SpareSimian]

This shows up in bag addons that use the Masque addon. A workaround is offered here: SFX-WoW/Masque#406